How To pass 2 dimensional array of strings to a function

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  1. #1
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    How To pass 2 dimensional array of strings to a function

    Hello,
    How To pass 2 dimensional array of strings to a function??at a go?
    means i dont want to pass address of each string 1 by 1..but want to pass whole 2D array string at a go?

  2. #2
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    and ya those strings are local to main() not the global ones

  3. #3
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    Quote Originally Posted by chottachatri View Post
    Hello,
    How To pass 2 dimensional array of strings to a function??at a go?
    means i dont want to pass address of each string 1 by 1..but want to pass whole 2D array string at a go?
    Maybe it's too early for me, but I don't see why you don't just pass the base address of the array, to the function.

    What's this "pass address of each string 1 by 1", stuff about?

    Would you show the relevant code in a post and surround it with the forum's code tags, please?

  4. #4
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    This is what i mean passing address of each string 1 by 1

    Code:
    #include <string.h>
    #include <stdio.h>
    void function(char *temp)
    {
    printf("&#37;s\n",temp);
    
    }
    void main()
    {
    int i,n;
    char temp[10][30];
    printf("\n\nHow Many Names Do You Want To Enter :");
    scanf("%d",&n);
    for(i=0;i<n;i++)
    {
      printf("\n\nEnter Name ->%d :",i+1);
      flushall();
      gets(temp[i]);
    }
    for(i=0;i<n;i++)
    {
     function(temp[i]);
    }
    getch();
    }
    Look at the above code each string is passed 1 by 1 in loop but i dont want to do that instead of loop i just want to pass the address a single time. How is it possible?

  5. #5
    C++ Witch laserlight's Avatar
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    You might write the function as:
    Code:
    void print_strings(char arr[][30], size_t size)
    {
        size_t i;
        for (i = 0; i < size; ++i)
        {
            printf("&#37;s\n", arr[i]);
        }
    }
    You would then call it as:
    Code:
    print_strings(temp, 10);
    Incidentally, please read our wiki FAQ concerning void main and [url=http://cpwiki.sourceforge.net/Gets]gets[/man] to find out what is wrong with them. You should also indent your code better.
    Last edited by laserlight; 01-23-2008 at 06:03 AM. Reason: Corrected the example code.
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  6. #6
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    do this:
    Code:
    void func(char** names, n)
    {
    for (int i=0; i<n; i++) puts(names[i]);
    }
    
    // then call like this:
    func(temp, n);

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    duh! laserlight is, fast like laser! fast like light!

  8. #8
    CSharpener vart's Avatar
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    probably becasu temp is declared as char temp[10][30]
    print_strings should be declared as
    Code:
    void print_strings(char arr[][30], size_t size);
    and not char**

    PS. And i should be declared as size_t not int
    Last edited by vart; 01-23-2008 at 06:00 AM.
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

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    Ok laserlight thank you very much! excellent! and ya i will use int main from now onwards

  10. #10
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    print_strings should be declared as

    And i should be declared as size_t not int
    Indeed, I overlooked both, so I shall make the fixes.
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    Ok now can anybody tell me how to do the same job with integer array??i mean please can anybody give me code for that? i have done it by 1 method but anybody knows a sweet and short method for it then please tell me?

    Code:
    #include <stdio.h>
    void print(int *a,int m,int n)
    {
     int i,j;
     for(i=0;i<m;i++)
     {
       for(j=0;j<n;j++)
       {
         printf("&#37;d ",*(a+i*n+j));
       }
         printf("\n");
     }
    
    }
    
    int main(void)
    {
     int a[3][3],i,k=1,j;
     for(i=0;i<3;i++)
     {
       for(j=0;j<3;j++)
       {
         a[i][j]=k++;
       }
     }
     print(&a[0][0],3,3);
     return 0;
    }
    Also explain me the funtion of size_t i haven't come across that function
    Last edited by chottachatri; 01-23-2008 at 06:23 AM.

  12. #12
    C++ Witch laserlight's Avatar
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    If you base your new code on my corrected example, you should have concluded that:
    Code:
    void print(int *a,int m,int n)
    should be:
    Code:
    void print(int a[][3],int m,int n)
    and that:
    Code:
    print(&a[0][0],3,3);
    should be:
    Code:
    print(a, 3, 3);
    Also, you can use a normal array subscript with a[i][j] instead of trying to compute the array index yourself.

    By the way, I think that an indentation of just one space may be too little. Typically about four spaces would be optimal.
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  13. #13
    CSharpener vart's Avatar
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    one dimention parameter is enough - second is hardcoded
    Code:
    void print(int a[][3],int m)
    The first 90% of a project takes 90% of the time,
    the last 10% takes the other 90% of the time.

  14. #14
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    Quote Originally Posted by manav View Post
    do this:
    Code:
    void func(char** names, n)
    {
    for (int i=0; i<n; i++) puts(names[i]);
    }
    
    // then call like this:
    func(temp, n);
    A double pointer won't work as a replacement for a 2D array - it only works the other way around, that you can make a 2D array by using a double pointer. If you are going to use a double pointer, you will have to allocate "rows" number of pointers, then assign each pointer to the first element of the rows.

    --
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  15. #15
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    > but anybody knows a sweet and short method for it then please tell me?
    Yeah, it's called copy and paste.

    If this is your array,
    int arr[2][3][4];

    Then this is your function prototype
    void func ( int arr[2][3][4] );


    Yes, you can then fiddle with the prototype to change it into either of these forms, but you don't buy a lot. Some compilers will warn about the left-most dimension not being empty, but apart from that, it's good.
    Alternatives:
    void func ( int arr[][3][4] );
    void func ( int (*arr)[3][4] );


    Irrespective of the form you choose to write the function prototype / declaration, it would be called with
    func ( arr );

    And the usual array access subscripts you would use if the array were in scope will still do what you want inside the function.
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