动态添加两个矩阵； 第 27 和 41 行错误

Question

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

int** addMatrix(int**, int, int, int**);

int main(void)
{
    int i, j, m, n, **p, **q, **sum; //i = row, j = column

    printf("Enter the size of the row: ");
    scanf("%d", &m);

    printf("Enter the size of the col: ");
    scanf("%d", &n);

    p = (int**)malloc(m * sizeof(int*));

    for(i=0; i<n; i++)
    {
        p[i] = (int*)malloc(n * sizeof(int));
    } 

    printf("Enter the elements of the Matrix M:\n"); //taking input
    for(i=0; i<m; i++)
    {
        for(j=0; j<n; j++)
           scanf("%d", ((p+i)+j)); // LINE 27
    }

    q = (int**)malloc(m * sizeof(int*));

    for(i=0; i<n; i++)
    {
        q[i] = (int*)malloc(n * sizeof(int));
    } 

printf("Enter the elements of the Matrix N:\n");
for(i=0; i<m; i++)
{
    for(j=0; j<n; j++)
       scanf("%d", ((q+i)+j)); // LINE 41
}

sum = addMatrix(p, m, n, q);

printf("Vector Sum:\n");
for(i=0; i<m; i++)
{
    for(j=0; j<n; j++)
        printf("%d ", *(*(sum+i)+j));
    printf("\n");
}
}

int** addMatrix(int **p, int m, int n, int **q)
{
int i, j, **add;
add = (int**)malloc(m * sizeof(int*));

for(i=0; i<n; i++)
{
    add[i] = (int*)malloc(n * sizeof(int));
} 

for(i=0; i<m; i++)
{
    for(j=0; j<n; j++)
        *(*(add+i)+j) = *(*(p+i)+j) + *(*(q+i)+j);
}    
return add;
}

main.c:27:21: warning: format '%d' expects argument of type 'int *', but argument 2 has type 'int **' [-Wformat=] main.c:41:21: warning: format '%d' expects argument of type 'int *', but argument 2 has type 'int **' [-Wformat=] the lines for taking the input of the matrix. this is the error I am getting.

Answer 1

The for loops like this

for(i=0; i<n; i++)
{
    p[i] = (int*)malloc(n * sizeof(int));
} 

are wrong. You have to use the variable m (the number of rows) instead of n (the number of columns)

for(i=0; i<m; i++)
{
    p[i] = (int*)malloc(n * sizeof(int));
} 

The calls of scanf like this

scanf("%d", ((p+i)+j));

are also wrong.

You have to write

scanf("%d", *(p+i)+j );

The expression *(p+i)+j is equivalent to p[i] + j that can be also written like &p[i][j] .

And you should free all the allocated memory before exiting the program.

In general you should check whether values for the variables m and n are valid and whether memory was allocated successfully. And it will be better if the variables m and n will have an unsigned integer type as for example size_t instead of the signed integer type int .