Like Tree9Likes

Problem with 'Matrix Multiplication using Pointers'

This is a discussion on Problem with 'Matrix Multiplication using Pointers' within the C Programming forums, part of the General Programming Boards category; Hello C Gurus, I am writing a C prog for Matrix Multiplication of X rows and Y cols using Pointers ...

  1. #1
    Registered User
    Join Date
    Jul 2012
    Posts
    10

    Problem with 'Matrix Multiplication using Pointers'

    Hello C Gurus,

    I am writing a C prog for Matrix Multiplication of X rows and Y cols using Pointers but getting warning and error:

    Warning : Suspicious pointer conversion
    Error : Illegal use of pointer // in multiplication func

    Not sure what I am missing?

  2. #2
    Registered User
    Join Date
    Jul 2012
    Posts
    10
    Here is the code :

    Code:
      #include<stdio.h>
      #include<conio.h>
    
      void input(int**x,int*p1,int*p2) //accepting matix from user
       {
        register int i,j,f;
        do
        {
         f=0;
         printf("\nenter no. of rows matrix[<=10]::");//no. of rows & validation
         scanf("%d",p1);
         if(*p1>0&&*p1<=10)
         f=0;
          else
          {
            printf("/ninvalid input");
            f=1;
          }
        }
       while(f==1);
       do
       {
        f=0;
        printf("\nenter no. of colomns for matrix[<=10]::");//no of cloumns &validation for it
        scanf("%d",p2);
        if(*p2>0&&*p2<=10)
        f=0;
        else
          {
           printf("/ninvalid input");
           f=1;
          }
        }while(f==1);
    
         for(i=0;i<*p1;i++)
          {
           for(j=0;j<*p2;j++)
            {
              printf("enter element in %d row and %d coloumn::",i+1,j+1);
              scanf("%d",(*(x+i)+j));
            }
           }
       }
    
        void display(int **x,int *p1,int *p2)//printing matrix
          {
           register int i,j;
            for(i=0;i<*p1;i++)
             {
              for(j=0;j<*p2;j++)
               {
                printf("   %d  ",(*(*(x+i)+j)));
                }
                printf("\n");
              }
            }
    
       void add(int **x,int **y,int *p1,int *p2) //addition of matrix
        {
          register  int i,j;
           int **c;
            for(i=0;i<*p1;i++)
             {
              for(j=0;j<*p2;j++)
               {
               (*(*(c+i)+j))=(*(*(x+i)+j))+(*(*(y+i)+j));
               }
             }
              display(c,p1,p2);
        }
    
       void subs(int**a,int**b,int*p1,int*p2)//substrction of matrix
        {
          register int i,j;
           int **d;
            for(i=0;i<*p1;i++)
             {
              for(j=0;j<*p2;j++)
               {
                 (*(*(d+i)+j))=(*(*(a+i)+j))+(*(*(b+i)+j));
               }
             }
            display(d,p1,p2);
        }
    
      void mul(int **x,int**y,int **e,int*p1,int*p2,int*p3)//multiplication
        {
         register int i,j,k;
         int sum;
    
         for(i=0;i<*p1;i++)
          {
           for(j=0;j<*p2;j++)
            {
             sum=0;
             for(k=0;k<*p3;k++)
             {
              sum=sum+((*(*(x+i)+k))*(*(*(y+k)+j)));
             }
             *(*(e+i)+k)=sum;
            }
          }
        }
    
    int min(int*a,int *p1) //finding minimum from array
     {
      int temp,i,j;
      for(i=0;i<*p1;i++)
       {
         for(j=0;j<*p1;j++)
           {
            if((*(a+i))<(*(a+j)))
            {
             temp=(*(a+i));
             (*(a+i))=(*(a+j));
             (*(a+j))=temp;
            }
           }
       }
       return a[0];
     }
    
     int max(int *a,int*p1)//finding maximum of array
      {
      int temp,i,j;
      for(i=0;i<*p1;i++)
       {
         for(j=0;j<*p1;j++)
           {
            if((*(a+i))>(*(a+j)))
            {
             temp=(*(a+i));
             (*(a+i))=(*(a+j));
             (*(a+j))=temp;
            }
           }
       }
       return a[0];
     }
    
    
    
    void sad(int**c,int*m,int*n) //finding saddle point
      {
       int i,j,row[10],col[10],temp1[10],temp2[10],y,z;
    
       for(i=0;i<*m;i++)
        {
        for(j=0;j<*n;j++)
         {
          *(row+j)=(*(*(c+i)+j));
          *(col+j)=(*(*(c+j)+i));
         }
          *(temp1+i)=max(row,&n);
          *(temp2+i)=min(col,&m);
        }
         y=min(temp1,&m);
         z=max(temp2,&n);
    
       if(y==z)
          printf("  %d",y);
       else
         printf("saddle point is not present");
      }
      void trans(int**x,int*m,int*n)//printing transpose
       {
        int i,j;
        int y[10][10];
        for(i=0;i<*m;i++)
         {
          for (j=0;j<*n;j++)
           {
            *(*(y+j)+i)=*(*(x+i)+j);
           }
         }
          display(y,n,m);
       }
    
      void main()
      {
       int a[10][10],b[10][10],c[10][10]; //intialisation
       void input(int**,int*,int*);    //user defined functions
       void display(int**,int*,int*);
       void add(int**,int**,int*,int*);
       void subs(int**,int**,int*,int*);
       void mul(int**,int**,int**,int*,int*,int*);
       int min(int*,int*);
       int max(int*,int*);
       void sad(int**,int*,int*);
       void trans(int**,int*,int*);
       int ch,m,n,m1,n1,flg,**ptr1,**ptr2;
       char s;
        do
          {
           clrscr();
           printf("\n\n matrix A\n");
           input(a,&m,&n);
           display(a,&m,&n);
           printf("\n\n matrix B\n");
           input(b,&m1,&n1);
           display(b,&m1,&n1);
    
           flg=0;
           clrscr();
           printf("\n\n matrix A\n");
           display(a,&m,&n);
           printf("\n\n matrix B\n");
           display(b,&m1,&n1);
           printf("\n\nwhich matrix operation want to perform\n\t 1::Addition of matrix\n\t 2::Substraction of matrix\n\t 3::Multiplication of matrix\n\t 4::Find saddle point\n\t 5::Transpose\n\t 6::Exit\n\n Enter choice!!!");
           scanf("%d",&ch);
    
        switch(ch)          //taking choice
         {
          case 1: if(m==m1&&n==n1)
                   {
                    printf("\n\t addition of given matrices is=\n");
                    add(a,b,&m,&n);
                   }
                   else
                   {
                    printf("\n\taddition not possible");
                   }
                   break;
    
          case 2:if(m==m1&&n==n1)
                   {
                    printf("\n\t substraction of given matrices is=\n");
                    subs(a,b,&m,&n);
                   }
                   else
                   {
                    printf("\n\tsubstraction not possible");
                   }
                   break;
          case 3:if(n==m1)
                  {
                   printf("\n\t multiplication of given matrix is=\n");
                   mul(a,b,c,&m,&n,&n1);
                   display(c,&m,&n1);
                  }
    
                 else
                  {
                  printf("\n\tmultiplication not possible");
                  }
                 break;
         case 4: printf("\n\tsaddle point in matrix A is=");
                  sad(a,&m,&n);
    
                 printf("\n\n\t sadddle point in matrix B is=");
                  sad(b,&m1,&n1);
    
                  break;
          case 5: printf(" trnaspose of matrices are");
                  printf("\n\n matrix A\n");
                  trans(a,&m,&n);
                  printf("\n\n matrix B\n");
                  trans(b,&m1,&n1);
                  break;
    
          case 6: printf("do u want to exit?(y/n)");
                  scanf(" %c",&s);
                  break;
          default: printf("enter valid choice");
    
          }
          getch();
    
               if(s=='y')
                 flg=0;
               else
                 flg=1;
         }
         while(flg==1);
        getch();
      }
    Last edited by JennyG; 07-27-2012 at 10:06 PM.

  3. #3
    Registered User
    Join Date
    Jun 2005
    Posts
    5,871
    Try expressing the function in terms of arrays. If you can't do that, you will have no hope of doing the same thing using pointers.
    Right 98% of the time, and don't care about the other 3%.

  4. #4
    Registered User
    Join Date
    Jul 2012
    Posts
    10
    Thanks grumpy.
    Sorry Im bit new in C, im not sure what you mean exactly? Can you please paste sample?

  5. #5
    Algorithm Dissector iMalc's Avatar
    Join Date
    Dec 2005
    Location
    New Zealand
    Posts
    6,266
    Some of the regular tips we give people that apply to you:
    • Don't use the 'register' keyword. At best it's just a gimmick for noobs nowdays, and using it is not actually beneficial.
    • a[b] and *(a + b) are the same. Use the syntax that is cleaner.
    • main should return int, not void.
    • Don't delete parameter names from function prototypes, and preferably don't put them inside functions.
    • A little whitespace never hurt anyone:
      Code:
      if (*p1 > 0 && *p1 <= 10)

    Also, using f or flg as a "flag" isn't very meaningful, nor is assigning integer values and declaring it as an int. The name of the variable should tell you what it is used for, and you should use the typical typedef for a boolean and defines for TRUE and FALSE. Preferably it would be switched around to be worded in a positive manner too, to avoid double-negatives. E.g.
    Code:
    BOOL inputIsValid;
    inputIsValid = TRUE;
    My homepage
    Advice: Take only as directed - If symptoms persist, please see your debugger

    Linus Torvalds: "But it clearly is the only right way. The fact that everybody else does it some other way only means that they are wrong"

  6. #6
    Registered User
    Join Date
    Jul 2012
    Posts
    10
    Thanks for the info.
    Can you please help me to fix the above code?
    Appreciate your help !

  7. #7
    and the hat of wrongness Salem's Avatar
    Join Date
    Aug 2001
    Location
    The edge of the known universe
    Posts
    32,341
    All your function prototypes and declarations are wrong.

    To pass these arrays to a function,
    int a[10][10],b[10][10],c[10][10]; //intialisation

    You need to declare the array parameter as
    void input(int[][10],int*,int*); //user defined functions

    The "arrays-become-pointers" rule is NOT recursive - it applies only to the left-most dimension of an array.
    Strictly speaking, the parameter type in the function should be int (*)[10] (a pointer to an array of 10 int's).
    But for ease of typing, the int[][10] notation works just as well.



    Why you shouldn't write 100's of lines of code and then post "it doesn't work"
    A development process
    You should have made sure that say "input" and "print" worked before charging ahead with the same mistakes in all the add/sub/mul/.... functions.
    AndiPersti likes this.
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

  8. #8
    Registered User
    Join Date
    May 2012
    Posts
    1,066
    Quote Originally Posted by JennyG View Post
    Can you please help me to fix the above code?
    Easy: Start from scratch.

    After removing the non-standard getch()- and clrscr()-functions, I still get 57(!) lines of warning messages:
    Code:
    $ gcc -g -Wall -Wextra -o test test.c
    test.c: In function ‘sad’:
    test.c:153:7: warning: passing argument 2 of ‘max’ from incompatible pointer type [enabled by default]
    test.c:122:6: note: expected ‘int *’ but argument is of type ‘int **’
    test.c:154:7: warning: passing argument 2 of ‘min’ from incompatible pointer type [enabled by default]
    test.c:104:5: note: expected ‘int *’ but argument is of type ‘int **’
    test.c:156:6: warning: passing argument 2 of ‘min’ from incompatible pointer type [enabled by default]
    test.c:104:5: note: expected ‘int *’ but argument is of type ‘int **’
    ...
    Nevertheless I've tried to start the program:
    Code:
    $ ./test
    
    
    matrix A
    
    enter no. of rows matrix[<=10]::4
    
    enter no. of colomns for matrix[<=10]::3
    enter element in 1 row and 1 coloumn::1
    Segmentation fault
    It crashes even before I can choose the multiplication!

    Instead of dumping a big non-working program on us, try to simplify your problem to a short example.
    Also read How To Ask Questions The Smart Way (especially "Be precise and informative about your problem" and "Volume is not precision")

    Bye, Andreas

  9. #9
    Registered User
    Join Date
    Jul 2012
    Posts
    10
    Thanks for info again.
    The code works fine on Windows for Add, Sub and everything but just not for Mul and hence need help in understanding the fix in above code.

  10. #10
    Algorithm Dissector iMalc's Avatar
    Join Date
    Dec 2005
    Location
    New Zealand
    Posts
    6,266
    Quote Originally Posted by JennyG View Post
    The code works fine on Windows for Add, Sub and everything but just not for Mul
    Rubbish. If you're telling us that the add method posted above is working, then you are horribly mistaken.
    The code you're posted is writing through an uninitialised double-pointer and reading through pointers with the wrong levels of indirection. That isn't even close to something that could ever "work". On Windows it is very predictable that it will crash.
    It will never work until you're fixed up the most important things that have been mentioned above.

    If you have some other fixed up code that actually runs now, you should post that. We aren't going to write it for you. The more you try and apply the help given and post what you've tried, and the more you ask specific questions, the quicker you'll get to something that works.
    My homepage
    Advice: Take only as directed - If symptoms persist, please see your debugger

    Linus Torvalds: "But it clearly is the only right way. The fact that everybody else does it some other way only means that they are wrong"

  11. #11
    Registered User
    Join Date
    Jul 2012
    Posts
    10
    Thanks guys. Sorry for my terrible mistake. I pasted wrong code above.
    The proper code is here (with 0 errors and a warning 'Suspicious pointer conversion')
    Code executes without an issue for all options but multiplication output is still coming up wrong.

    Code:
      void input(int(*x)[10],int*p1,int*p2) //accepting matix from user
       {
        register int i,j,f;
        int*k;
        do
        {
         f=0;
         printf("\nenter no. of rows matrix[<=10]::");//no. of rows & validation
         scanf("%d",p1);
         if(*p1>0&&*p1<=10)
         f=0;
          else
          {
            printf("/ninvalid input");
            f=1;
          }
        }
       while(f==1);
       do
       {
        f=0;
        printf("\nenter no. of colomns for matrix[<=10]::");//no of cloumns &validation for it
        scanf("%d",p2);
        if(*p2>0&&*p2<=10)
        f=0;
        else
          {
           printf("/ninvalid input");
           f=1;
          }
        }while(f==1);
    
         for(i=0;i<*p1;i++)
          {
           k=x+i;
           for(j=0;j<*p2;j++)
            {
              printf("enter element in %d row and %d coloumn::",i+1,j+1);
              scanf("%d",(k+j));
            }
           }
       }
    
        void display(int(*x)[10],int *p1,int *p2)//printing matrix
          {
           register int i,j;
           int*k;
            for(i=0;i<*p1;i++)
             {
              k=x+i;
              for(j=0;j<*p2;j++)
               {
                printf("   %d  ",(*(k+j)));
                }
                printf("\n");
              }
            }
    
       void add(int (*x)[10],int(*y)[10],int *p1,int *p2) //addition of matrix
        {
          register  int i,j;
           int c[10][10],*k,*l,*p;
            for(i=0;i<*p1;i++)
             {
              k=x+i;
              l=y+i;
              p=c+i;
              for(j=0;j<*p2;j++)
               {
               (*(p+j))=(*(k+j))+(*(l+j));
               }
             }
              display(c,p1,p2);
        }
    
      void subs(int(*x)[10],int(*y)[10],int*p1,int*p2)//substrction of matrix
        {
          register  int i,j;
           int c[10][10],*k,*l,*p;
            for(i=0;i<*p1;i++)
             {
              k=x+i;
              l=y+i;
              p=c+i;
              for(j=0;j<*p2;j++)
               {
               (*(p+j))=(*(k+j))-(*(l+j));
               }
             }
              display(c,p1,p2);
        }
    
    
    
    
      void mul(int(*x)[10],int(*y)[10],int(*e)[10],int*p1,int*p2,int*p3)//multiplication
        {
         register int i,j,k;
         int sum,*s,*t,*r,z,h;
    
         for(i=0;i<*p1;i++)
          {
           s=x+i;
           r=e+i;
           for(j=0;j<*p2;j++)
            {
             sum=0;
             for(k=0;k<*p3;k++)
             {
              t=y+k;
              z=*(s+k);
              h=*(y+j);
              sum=sum+(z*h);
             }
             *(r+k)=sum;
            }
          }
        }
    
    int min(int a[],int *p1) //finding minimum from array
     {
      int temp,i,j;
      for(i=0;i<*p1;i++)
       {
         for(j=0;j<*p1;j++)
           {
            if(a[i]<a[j])
            {
             temp=a[i];
             a[i]=a[j];
             a[j]=temp;
            }
           }
       }
       return a[0];
     }
    
     int max(int a[],int*p1)//finding maximum of array
      {
      int temp,i,j;
      for(i=0;i<*p1;i++)
       {
         for(j=0;j<*p1;j++)
           {
            if(a[i]>a[j])
            {
             temp=a[i];
             a[j]=a[j];
             a[j]=temp;
            }
           }
       }
       return a[0];
     }
    
    
    
    void sad(int(*c)[10],int*m,int*n) //finding saddle point
      {
       int i,j,row[10],col[10],temp1[10],temp2[10],y,z,*p,*q;
    
       for(i=0;i<*m;i++)
        {
        p=c+i;
        for(j=0;j<*n;j++)
         {
          q=c+j;
         *(row+j)=*(p+j);
         *(col+j)=*(q+i);
         }
          *(temp1+i)=max(row,n);
          *(temp2+i)=min(col,m);
    
        }
         y=min(temp1,m);
         z=max(temp2,n);
    
       if(y==z)
          printf("  %d",y);
       else
         printf("saddle point is not present");
      }
    
     void trans(int(*x)[10],int*m,int*n)//printing transpose
       {
        int i,j,*p,*q;
        int y[10][10];
        for(i=0;i<*m;i++)
         {
          p=x+i;
          for (j=0;j<*n;j++)
           {
           q=y+j;
            *(q+i)=*(p+j);
           }
         }
          display(y,n,m);
       }
    
      void main()
      {
       int a[10][10],b[10][10],c[10][10]; //intialisation
       void input(int(*)[],int*,int*);    //user defined functions
       void display(int(*)[],int*,int*);
       void add(int(*)[],int(*)[],int*,int*);
       void subs(int(*)[],int(*)[],int*,int*);
       void mul(int(*)[],int(*)[],int(*)[],int*,int*,int*);
       int min(int[],int*);
       int max(int[],int*);
       void sad(int(*)[],int*,int*);
       void trans(int(*)[],int*,int*);
       int ch,m,n,m1,n1,flg;
       char s;
        do
          {
           clrscr();
           printf("\n\n matrix A\n");
           input(a,&m,&n);
           display(a,&m,&n);
           printf("\n\n matrix B\n");
           input(b,&m1,&n1);
           display(b,&m1,&n1);
    
           flg=0;
           clrscr();
           printf("\n\n matrix A\n");
           display(a,&m,&n);
           printf("\n\n matrix B\n");
           display(b,&m1,&n1);
           printf("\n\nwhich matrix operation want to perform\n\t 1::Addition of matrix\n\t 2::Substraction of matrix\n\t 3::Multiplication of matrix\n\t 4::Find saddle point\n\t 5::Transpose\n\t 6::Exit\n\n Enter choice!!!");
           scanf("%d",&ch);
    
        switch(ch)          //taking choice
         {
          case 1: if(m==m1&&n==n1)
                   {
                    printf("\n\t addition of given matrices is=\n");
                    add(a,b,&m,&n);
                   }
                   else
                   {
                    printf("\n\taddition not possible");
                   }
                   break;
    
          case 2:if(m==m1&&n==n1)
                   {
                    printf("\n\t substraction of given matrices is=\n");
                    subs(a,b,&m,&n);
                   }
                   else
                   {
                    printf("\n\tsubstraction not possible");
                   }
                   break;
          case 3:if(n==m1)
                  {
                   printf("\n\t multiplication of given matrix is=\n");
                   mul(a,b,c,&m,&n,&n1);
                   display(c,&m,&n1);
                  }
    
                 else
                  {
                  printf("\n\tmultiplication not possible");
                  }
                 break;
         case 4: printf("\n\tsaddle point in matrix A is=");
                  sad(a,&m,&n);
    
                 printf("\n\n\t sadddle point in matrix B is=");
                  sad(b,&m1,&n1);
    
                  break;
          case 5: printf(" trnaspose of matrices are");
                  printf("\n\n matrix A\n");
                  trans(a,&m,&n);
                  printf("\n\n matrix B\n");
                  trans(b,&m1,&n1);
                  break;
    
          case 6: printf("do u want to exit?(y/n)");
                  scanf(" %c",&s);
                  break;
          default: printf("enter valid choice");
    
          }
          getch();
    
               if(s=='y')
                 flg=0;
               else
                 flg=1;
         }
         while(flg==1);
        getch();
      }
    Last edited by JennyG; 07-28-2012 at 07:46 PM.

  12. #12
    Registered User
    Join Date
    May 2012
    Location
    Arizona, USA
    Posts
    383
    You get only one warning from all of that? Do you have compiler warnings suppressed or something? I get 27 warnings at the default warning level and 33 with all warnings enabled.

    Most of the warnings are of this form:
    Code:
    warning: assignment from incompatible pointer type
    It appears to have all or most of the same issues as others have mentioned already.

  13. #13
    Algorithm Dissector iMalc's Avatar
    Join Date
    Dec 2005
    Location
    New Zealand
    Posts
    6,266
    After #including conio.h and commenting out the clrscr calls, I get 30 errors. Not just warnings that let you mistakenly produce a program that may not behave correctly, but actual errors. The compiler outright refuses to produce any code at all. Errors such as:
    Code:
    error C2440: '=' : cannot convert from 'int (*)[10]' to 'int *'
    1>        Types pointed to are unrelated; conversion requires reinterpret_cast, C-style cast or function-style cast
    These errors suggest that one can force the compiler to accept the nonsense it is given by giving it a brutal cast.

    Plus where you aparently get a warning, I get an even worse error:
    Code:
    error C2440: '=' : cannot convert from 'int [10]' to 'int'
    1>        There is no context in which this conversion is possible
    This one is even worse, and I'm surprised that any kind of cast can manage to force the compiler to take it.


    A compiler that blatently accepts the badly wrong code you are giving it here without so much as a warning, is not a good learning tool. It is not advising you of your mistakes, so you are not able to learn from them. I fear you must be using that Turbid Crap++ or something nearly as awful.
    If ever there was a time where one should follow the advice of changing to a better compiler, this would be it. You wouldn't ask a drunk and high guy with violent tendencies and flamethrower to teach you rocket science. So don't ask a dead beat useless as <insert colourful word here> compiler to teach you how to program.

    Also, when you want help, ignoring suggestions is one of the worst things you can do. If you don't understand the advice given then you should either query it, or say why you are plan to do nothing in regards to it.
    My homepage
    Advice: Take only as directed - If symptoms persist, please see your debugger

    Linus Torvalds: "But it clearly is the only right way. The fact that everybody else does it some other way only means that they are wrong"

  14. #14
    Registered User
    Join Date
    Jul 2012
    Posts
    10
    Thanks all of you. code updated and now works for all cases (on windows - TC)
    However im still unable to remove 15 warnings for 'Suspicious pointer conversion'
    Can you try to run this code on your system?

    Code:
     void input(int(*x)[10],int*p1,int*p2) //accepting matix from user
       {
        register int i,j,f;
        int*k;
        do
         {
          f=0;
          printf("\nenter no. of rows matrix[<=10]::");//no. of rows & validation
          scanf("%d",p1);
           if(*p1>0&&*p1<=10)
            f=0;
           else
            {
             printf("/ninvalid input");
             f=1;
            }
        }
       while(f==1);
    
       do
        {
         f=0;
         printf("\nenter no. of colomns for matrix[<=10]::");//no of cloumns &validation for it
         scanf("%d",p2);
          if(*p2>0&&*p2<=10)
            f=0;
          else
    
           {
           printf("/ninvalid input");
           f=1;
          }
        }
        while(f==1);
    
         for(i=0;i<*p1;i++)
          {
           k=x+i;
           for(j=0;j<*p2;j++)
            {
              printf("enter element in %d row and %d coloumn::",i+1,j+1);
              scanf("%d",(k+j));
            }
           }
       }
    
        void display(int(*x)[10],int *p1,int *p2)//printing matrix
          {
           register int i,j;
           int*k;
            for(i=0;i<*p1;i++)
             {
              k=x+i;
              for(j=0;j<*p2;j++)
               {
                printf("\t%d",(*(k+j)));
                }
                printf("\n");
              }
            }
    
       void add(int (*x)[10],int(*y)[10],int *p1,int *p2) //addition of matrix
        {
          register  int i,j;
           int c[10][10],*k,*l,*p;
            for(i=0;i<*p1;i++)
             {
              k=x+i;
              l=y+i;
              p=c+i;
              for(j=0;j<*p2;j++)
               {
               (*(p+j))=(*(k+j))+(*(l+j));
               }
             }
              display(c,p1,p2);
        }
    
      void subs(int(*x)[10],int(*y)[10],int*p1,int*p2)//substrction of matrix
        {
          register  int i,j;
           int c[10][10],*k,*l,*p;
            for(i=0;i<*p1;i++)
             {
              k=x+i;
              l=y+i;
              p=c+i;
              for(j=0;j<*p2;j++)
               {
               (*(p+j))=(*(k+j))-(*(l+j));
               }
             }
              display(c,p1,p2);
        }
    
    
    
    
      void mul(int(*x)[10],int(*y)[10],int*m,int*n,int*n1)//multiplication
        {
         register int i,j,k;
         int sum,e[10][10],*ip,*jp,*kp;
    
         for(i=0;i<*m;i++)
          {
           ip=x+i;
           jp=e+i;
           for(j=0;j<*n;j++)
            {
             sum=0;
             for(k=0;k<*n1;k++)
             {
              kp=(y+k);
              sum=sum+(*(ip+k))*(*(kp+j));
             }
            (*(jp+j))=sum;
            }
          }
          display(e,m,n1);
        }
    
    int min(int a[],int *p1) //finding minimum from array
     {
      int temp,i,j;
      for(i=0;i<*p1;i++)
       {
         for(j=0;j<*p1;j++)
           {
            if(a[i]<a[j])
            {
             temp=a[i];
             a[i]=a[j];
             a[j]=temp;
            }
           }
       }
       return a[0];
     }
    
     int max(int a[],int*p1)//finding maximum of array
      {
      int temp,i,j;
      for(i=0;i<*p1;i++)
       {
         for(j=0;j<*p1;j++)
           {
            if(a[i]>a[j])
            {
             temp=a[i];
             a[j]=a[j];
             a[j]=temp;
            }
           }
       }
       return a[0];
     }
    
    
    
    void sad(int(*c)[10],int*m,int*n) //finding saddle point
      {
       int i,j,row[10],col[10],temp1[10],temp2[10],y,z,*p,*q;
    
       for(i=0;i<*m;i++)
        {
        p=c+i;
        for(j=0;j<*n;j++)
         {
          q=c+j;
         *(row+j)=*(p+j);
         *(col+j)=*(q+i);
         }
          *(temp1+i)=max(row,n);
          *(temp2+i)=min(col,m);
    
        }
         y=min(temp1,m);
         z=max(temp2,n);
    
       if(y==z)
          printf(" %d",y);
       else
         printf("saddle point is not present");
      }
    
     void trans(int(*x)[10],int*m,int*n)//printing transpose
       {
        int i,j,*p,*q;
        int y[10][10];
        for(i=0;i<*m;i++)
         {
          p=x+i;
          for (j=0;j<*n;j++)
           {
           q=y+j;
            *(q+i)=*(p+j);
           }
         }
          display(y,n,m);
       }
    
      void main()
      {
       int a[10][10],b[10][10]; //intialisation
       void input(int(*)[],int*,int*);    //user defined functions
       void display(int(*)[],int*,int*);
       void add(int(*)[],int(*)[],int*,int*);
       void subs(int(*)[],int(*)[],int*,int*);
       void mul(int(*)[],int(*)[],int*,int*,int*);
       int min(int[],int*);
       int max(int[],int*);
       void sad(int(*)[],int*,int*);
       void trans(int(*)[],int*,int*);
       int ch,m,n,m1,n1,flg;
       char s;
    
           clrscr();
           printf("\n\n matrix A\n");
           input(a,&m,&n);
           display(a,&m,&n);
           printf("\n\n matrix B\n");
           input(b,&m1,&n1);
           display(b,&m1,&n1);
       do
        {
           flg=0;
           clrscr();
           printf("\n\n matrix A\n");
           display(a,&m,&n);
           printf("\n\n matrix B\n");
           display(b,&m1,&n1);
           printf("\n\nwhich matrix operation want to perform\n\t 1::Addition of matrix\n\t 2::Substraction of matrix\n\t 3::Multiplication of matrix\n\t 4::Find saddle point\n\t 5::Transpose\n\t 6::Exit\n\n Enter choice!!!");
           scanf("%d",&ch);
    
        switch(ch)          //taking choice
         {
          case 1: if(m==m1&&n==n1)
                   {
                    printf("\n\t addition of given matrices is=\n");
                    add(a,b,&m,&n);
                   }
                   else
                   {
                    printf("\n\taddition not possible");
                   }
                   break;
    
          case 2:if(m==m1&&n==n1)
                   {
                    printf("\n\t substraction of given matrices is=\n");
                    subs(a,b,&m,&n);
                   }
                   else
                   {
                    printf("\n\tsubstraction not possible");
                   }
                   break;
          case 3:if(n==m1)
                  {
                   printf("\n\t multiplication of given matrix is=\n");
                   mul(a,b,&m,&n,&n1);
                  }
    
                 else
                  {
                  printf("\n\tmultiplication not possible");
                  }
                 break;
         case 4: printf("\n\tsaddle point in matrix A is=");
                  sad(a,&m,&n);
    
                 printf("\n\n\t sadddle point in matrix B is=");
                  sad(b,&m1,&n1);
    
                  break;
          case 5: printf(" trnaspose of matrices are");
                  printf("\n\n matrix A\n");
                  trans(a,&m,&n);
                  printf("\n\n matrix B\n");
                  trans(b,&m1,&n1);
                  break;
    
          case 6: printf("do u want to exit?(y/n)");
                  scanf(" %c",&s);
                  break;
          default: printf("enter valid choice");
    
          }
          getch();
    
               if(s=='y')
                 flg=0;
               else
                 flg=1;
         }
         while(flg==1);
        getch();
      }

  15. #15
    ZuK
    ZuK is offline
    Registered User
    Join Date
    Aug 2005
    Location
    Austria
    Posts
    1,990
    it is always the same mistake
    you are adding an offset to an int(*x)[10] and expect the result to be a ponter to int -->> that is suspicious.

    do as salem has told you
    Code:
    void display(int(*x)[10],int *p1,int *p2)//printing matrix
    {
        register int i,j;
        int*k;
        for(i=0;i<*p1;i++)
        {
            // k=x+i;   <<-- wrong
            k=x[i];   // <<-- right
            for(j=0;j<*p2;j++)
            {
                printf("\t%d",(*(k+j)));
            }
            printf("\n");
        }
    }
    Kurt

Page 1 of 2 12 LastLast
Popular pages Recent additions subscribe to a feed

Similar Threads

  1. Replies: 6
    Last Post: 05-14-2011, 09:28 AM
  2. Problem in Matrix Multiplication (Using friend function)
    By wantsree in forum C++ Programming
    Replies: 3
    Last Post: 02-09-2011, 07:03 AM
  3. Hi, problem with pointers and matrix multiplication
    By Phadelity in forum C Programming
    Replies: 2
    Last Post: 11-23-2010, 10:53 PM
  4. Matrix Multiplication
    By Warped1 in forum C++ Programming
    Replies: 2
    Last Post: 11-05-2001, 10:48 PM

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21