Thread: Problem in arrays

Hi,


I'm making a little software, what make and sum array or matrices (I don't know in english )... I can make the first array, is fine, but in the second array, the program copy the last row on the other rows...


I need a help, please...


and sorry my english, I'm brazilian and ... my english isnt very good ...thank you


I use DEV C++ on Win Seven

Code:

int main(){     
     
      int i,j;
      int linA,colA;
      int mA[linA][colA];
      int aij,mult_i,mult_j;
      
      
      printf("### DETERMINANTE DE UMA MATRIZ ###\n\n\n");
//CRIANDO A MATRIZ
      printf("\n### MATRIZ A ###\n\n");
      
      printf("linhas ? "); //number of rows
      scanf("%i",&linA);
      
      printf("\n\ncolunas ? ");//number of columns
      scanf("%i",&colA);
      
      for(i=0; i<linA; i++)
      {
               for(j=0; j<colA; j++)
               {
                        printf("Digite o numero da %i linha, %i coluna : (MATRIZ A): ",i,j); //first number
                        scanf("%i",&mA[i][j]);
                        
                        }
             printf("\n");
               }
      
      for(i=0; i<linA; i++)
      {
               for(j=0; j<colA; j++)
               {
                        printf("%i ",mA[i][j]);
                        }
               printf("\n");
                        
                        }
                        
//CRIANDO A SEGUNDA MATRIZ - second array
      int linB,colB;    
      int mB[linB][colB];
      i=0;
      j=0;
      
      printf("\n### MATRIZ B ###\n\n");
       
      printf("linhas ? ");
      scanf("%i",&linB);
      
      printf("\n\ncolunas ? ");
      scanf("%i",&colB);
      
      for(i=0; i<linB; i++)
      {
               for(j=0; j<colB; j++)
               {
                        printf("Digite o numero da %i linha, %i coluna : (MATRIZ B): ",i,j);
                        scanf("%i",&mB[i][j]);
                        
                        }
             printf("\n");
               }
      
            for(i=0; i<linB; i++)
      {
               for(j=0; j<colB; j++)
               {
                        printf("%i ",mB[i][j]);
                        }
               printf("\n");
                        
                        }    

system("pause >> log");

}

Code:

int main(){    
      
      int i,j;
      int linA,colA;
      int mA[linA][colA]; // at this point linA and colA contain garbage

Kurt

What include files are you including? You need at least two for your program, stdio.h and stdlib.h.

Also, I doubt that your compiler supports the C99 standard so you should be using constants when you define your array size.


Jim

Originally Posted by jimblumberg

What include files are you including? You need at least two for your program, stdio.h and stdlib.h.

Also, I doubt that your compiler supports the C99 standard so you should be using constants when you define your array size.


Jim

Sorry, is

#include<stdio.h>#include<stdlib.h>

Tell me another compiler please =D

I use DEV C++ on Win Seven

Originally Posted by jimblumberg

Also, I doubt that your compiler supports the C99 standard ....

GCC supported VLA's long before C99 as an extension
Kurt

Originally Posted by ZuK

GCC supported VLA's long before C99 as an extension
Kurt

thanks

In my opinion, when learning the language you should avoid using compiler specific hacks. I suggest in this case you either use fixed array sizes, and limit your data entry to that number of elements or learn to use dynamic memory using malloc/free.

Jim

I agree. And I was never happy that gcc enabled its extensions by default.
Kurt

Don't use Dev-C++, it has a very old version of GCC

Originally Posted by Epy

Don't use Dev-C++, it has a very old version of GCC

Agree with Epu(metal slug i think). Go to a newer IDE

Originally Posted by std10093

Agree with Epu(metal slug i think). Go to a newer IDE

is that the DEV-C + + in college was recommended to be in Portuguese, but I'll look for this GCC

Well since you are using Windows your could also investigate Microsoft Visual C++ express edition, or Code::Blocks. Both are free and more up to date than DevC++.

Jim

Originally Posted by mathiasbenitez

is that the DEV-C + + in college was recommended to be in Portuguese, but I'll look for this GCC

In Greece too.But this is only for the very start of coding Netbeans,eclipse and Microsoft visual studio 2012 is what you could try...and of course what jim said