Array,pointer getting error [warning]Braces around scalar initializer

A is an array of int *, not a 2D array. Therefore, the initializers should be scalar values which are an int *.

If you have C99 or C11, you can rescue the code like this:

#include <stdio.h>

extern void printMatrix(int *x[], int y, int z);
extern void multiply(int *A[], int n1, int n2, int *B[], int n3, int n4, int *C[3]);

int main(void)
{
    int *A[3] = {(int []){1,1,1,1}, (int []){1,1,1,1}, (int []){1,1,1,1}};
    int *B[4] = {(int []){2,2,2}, (int []){2,22,2}, (int []){3,3,3}, (int []){3,3,3}};
    int *C[3];
    multiply(A, 1, 2, B, 3, 4, C);
    printf("A matrix:\n");
    printMatrix(A, 3, 4);
    printf("B matrix:\n");
    printMatrix(B, 4, 3);
    printf("C matrix:\n");
    printMatrix(C, 3, 3);
    printf("Hello, World!\n");
    return 0;
}

This uses C99 compound literals in the initializers.

However, you will need to be careful to allocate the right amount of space inside multiply() to store the data for each row in C. You'll also have to know how to release the allocated space.