Thread: Multiplying Two Matrix!

I'm Confused! What's the problem?
Please Help; Thanks.

Code:

#include <stdio.h>
#include <conio.h>
void input (int [][3], int, int [][4], int);
int mult (int [][3], int, int [][4], int);
void out (int [][4], int);
int main ()
{
    const int r = 2, c = 3;
    int mat1 [r][4], mat2 [c][4], mat [r][4];
    input (mat1, r, mat2, c);
    mult (mat1, r, mat2, c);
    mat = mult (mat1, r, mat2, c);
    out (mat, r);
    getch ();
    return 0;
}
void input (int mat1 [][3], int r, int mat2 [][4], int c)
{
     for (int i = 0; i < r; i++)
         for (int j = 0; j < 3; j++)
         {
             printf ("\nEnter mat1 [%d][%d]:\n", i, j);
             scanf ("%d", &mat1 [i][j]);
             }
             for (int i = 0; i < c; i++)
                 for (int j = 0; j < 4; j++)
                 {
                     printf ("\nEnter mat2 [%d][%d]:\n", i, j);
                     scanf ("%d", &mat2 [i][j]);
                     }
                     }
                     int mult (int mat1 [][3], int r, int mat2 [][4], int c)
                     {
                         int mat [2][4];
                         for (int i = 0; i < r; i++)
                             for (int j = 0; j < 4; j++)
                                 for (int k = 0; k < c; k++)
                                 mat [i][j] = mat1 [i][k] * mat2 [k][j];
                                 return mult;
                                 }
                                 void out (int mat [][4], int r)
                                 {
                                      printf ("\nThe produc of mat1 and mat2:\n");
                                      for (int i = 0; i < r; i++){
                                          for (int j = 0; j < 4; j++)
                                          printf ("%5d", mat [i][j]);
                                          printf ("\n");
                                          }
                                          }

You should put more effort into framing your question. What's the problem?

Learn to format your code right.

Code:

#include <stdio.h>
#include <conio.h>
void input (int [][3], int, int [][4], int);
int mult (int [][3], int, int [][4], int);
void out (int [][4], int);
int main ()
{
    const int r = 2, c = 3;
    int mat1 [r][4], mat2 [c][4], mat [r][4];
    input (mat1, r, mat2, c);
    mult (mat1, r, mat2, c);
    mat = mult (mat1, r, mat2, c);
    out (mat, r);
    getch ();
    return 0;
}
void input (int mat1 [][3], int r, int mat2 [][4], int c)
{
    for (int i = 0; i < r; i++)
        for (int j = 0; j < 3; j++)
        {
            printf ("\nEnter mat1 [%d][%d]:\n", i, j);
            scanf ("%d", &mat1 [i][j]);
        }
    for (int i = 0; i < c; i++)
        for (int j = 0; j < 4; j++)
        {
            printf ("\nEnter mat2 [%d][%d]:\n", i, j);
            scanf ("%d", &mat2 [i][j]);
        }
}
int mult (int mat1 [][3], int r, int mat2 [][4], int c)
{
    int mat [2][4];
    for (int i = 0; i < r; i++)
        for (int j = 0; j < 4; j++)
            for (int k = 0; k < c; k++)
                mat [i][j] = mat1 [i][k] * mat2 [k][j];
    return mult;
}
void out (int mat [][4], int r)
{
    printf ("\nThe produc of mat1 and mat2:\n");
    for (int i = 0; i < r; i++)
    {
        for (int j = 0; j < 4; j++)
            printf ("%5d", mat [i][j]);
        printf ("\n");
    }
}

Learn to compile with warnings on.
Read the warnings; fix the warnings.

Code:

mingw32-gcc.exe -Wall -std=c99  -O2     -c main.c -o obj\Release\main.o
main.c: In function 'main':
main.c:10:5: warning: passing argument 1 of 'input' from incompatible pointer type [enabled by default]
main.c:3:6: note: expected 'int (*)[3]' but argument is of type 'int (*)[4]'
main.c:11:5: warning: passing argument 1 of 'mult' from incompatible pointer type [enabled by default]
main.c:4:5: note: expected 'int (*)[3]' but argument is of type 'int (*)[4]'
main.c:12:5: warning: passing argument 1 of 'mult' from incompatible pointer type [enabled by default]
main.c:4:5: note: expected 'int (*)[3]' but argument is of type 'int (*)[4]'
main.c:12:9: error: incompatible types when assigning to type 'int[(unsigned int)r][4]' from type 'int'
main.c: In function 'mult':
main.c:39:5: warning: return makes integer from pointer without a cast [enabled by default]
main.c:34:9: warning: variable 'mat' set but not used [-Wunused-but-set-variable]