c - 返回一个数组

Question

我正在尝试使用以下代码添加两个矩阵:

    #include <stdio.h>
    int matrix (void)
    {
        int a[2][2];
        int b[2][2];
        int c[2][2];
        int i, j;
        for (i = 0; i < 2; ++i) {
            for (j = 0; j < 2; ++j) {
                    scanf("%d", &a[i][j]);
            }
        }
        for (i = 0; i < 2; ++i) {
            for (j = 0; j < 2; ++j) {
                    scanf("%d", &b[i][j]);
            }
        }
        for (i = 0; i < 2; ++i) {
            for (j = 0; j < 2; ++j) {
                    c[i][j] = a[i][j] + b[i][j];
            }
        }
        return c;
    }
    int main ()
    {
        int i, j;
        int c[2][2];
        c = matrix();
        for (i = 0; i < 2; ++i) {
            for (j = 0; j < 2; ++j) {
                    printf("%d", c[i][j]);
            }
            printf("\n");
        }
        return 0;
    }

上面的代码抛出了很多错误。请解释为什么我的编译器显示这么多错误。

编辑-我在编译上面的代码时使用了 GCC 4.4.3。

EDIT2 - 编译上述代码时出现以下错误和警告。

test.c: In function ‘matrix’:
test.c:23: warning: return makes integer from pointer without a cast
test.c:23: warning: function returns address of local variable
test.c: In function ‘main’:
test.c:29: error: incompatible types when assigning to type ‘int[2][2]’ from type ‘int’

Answer 1

按照您的意愿进行修复。

#include <stdio.h>

int (*matrix(void))[2]{//return pointer as int (*)[2]
    static int c[2][2];//Can not be used to return the automatic local variables.
    int a[2][2];
    int b[2][2];
    int i, j;
    for (i = 0; i < 2; ++i) {
        for (j = 0; j < 2; ++j) {
                scanf("%d", &a[i][j]);
        }
    }
    for (i = 0; i < 2; ++i) {
        for (j = 0; j < 2; ++j) {
                scanf("%d", &b[i][j]);
        }
    }
    for (i = 0; i < 2; ++i) {
        for (j = 0; j < 2; ++j) {
                c[i][j] = a[i][j] + b[i][j];
        }
    }
    return c;
}
int main (){
    int i, j;
    int (*c)[2];
    c = matrix();
    for (i = 0; i < 2; ++i) {
        for (j = 0; j < 2; ++j) {
            printf("%d ", c[i][j]);//remove &
        }
        printf("\n");
    }
    return 0;
}