#include<stdio.h>

void matrix_multiply(int x, int y, int z, int m1[][y], int m2[][z], int r[][z]);
int main(void)
{
    int x = 2;
    int y = 3;
    int z = 4;
   
     int m1[x][y] = {{2,-6},
                    {3,5},
                    { 1,-1},
    };
    int m2[y][z] = {{4,-2,-4,-5},
                   {-7,-3,5,7},
    };
   
    int r[x][z];
   
    matrix_multiply(m1,m2,r,x,y,z);
   
    return 0;

}

void matrix_multiply(int x,int y, int z,int m1[][y], int m2[][z], int r[][z])
{
   
    int i,j,k;
    int sum ;
  
  for(k = 0; k < z; k++)
    {
        for(j = 0; j < y; j++)
        {
            sum = 0;
            for(i = 0; i < 2; i++)
            {
                sum = sum + m1[x][i] * m2[i][y];
            }
            r[i][k] = sum;
            printf("%5d", r[i][k]);
        }
        printf("\n");
    }
}

定义函数的时候总是有错误，希望大神指点

[此贴子已经被作者于2017-1-24 15:10编辑过]

你总得贴出编译器给出的错误信息吧
否则让别人瞎猜？

#include<stdio.h>

void matrix_multiply(int x, int y, int z, int m1[][2], int m2[][4], int r[][4]);
int main(void)
{
    int x = 2;
    int y = 3;
    int z = 4;
   
     int m1[3][2] = {2,-6,       //数组下标不用变量
                     3,5,
                     1,-1};
    int m2[3][4] = {4,-2,-4,-5,
                   -7,-3,5,7,};
   
    int r[2][4];
   
    matrix_multiply(x,y,z,m1,m2,r);
   
    return 0;

}

void matrix_multiply(int x,int y, int z,int m1[][2], int m2[][4], int r[][4])
{
   
    int i,j,k;
    int sum ;
  
  for(k = 0; k < z; k++)
    {
        for(j = 0; j < y; j++)
        {
            sum = 0;
            for(i = 0; i < 2; i++)
            {
                sum = sum + m1[x][i] * m2[i][y];
            }
            r[i][k] = sum;
            printf("%5d", r[i][k]);
        }
        printf("\n");
    }
}

二维数组在作为形参时，他的列数必须是确定的

//定义数组是，下标是常量。
int m1[x][y] = {{2,-6},
                     {3,5},
                     { 1,-1},//这里多个逗号
     };

[此贴子已经被作者于2017-1-24 18:03编辑过]