迭代-嵌套for循环

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
//双层for循环
char *nestedForLoop(int n){
    //nested --嵌套
    int size = n * n * 26 + 1;
    char * res = malloc(size * sizeof(char));
    for(int i = 1; i <= n; i++){
        for(int j =1; j<= n; j++){
            char tmp[26];
            //snprintf()函数是为了防止缓冲区溢出，并把printf的输出内容格式化!
            snprintf(tmp, sizeof(tmp), "(%d,%d),", i, j);
            //往res后面添加(连接)字符串tmp
            strncat(res, tmp, size-strlen(res)-1);
        }
    }
    return res;
}
int main(){
    int n = 5;
    char * res = nestedForLoop(n);
    printf("%s", res);
    return 0;
}