C语言字符串插入函数：在指定位置插入字符

#include <stdio.h>
#include <string.h>

void insertc(char *str, char c, int n) {
    int len = strlen(str);
    if (n > len) {
        str[len] = c;
        str[len + 1] = '\0';
    } else {
        for (int i = len; i >= n; i--) {
            str[i + 1] = str[i];
        }
        str[n] = c;
    }
}

int main() {
    char str[100], c;
    int n;

    printf("请输入字符串：");
    fgets(str, 100, stdin);
    printf("请输入要插入的字符：");
    scanf("%c", &c);
    printf("请输入要插入的位置：");
    scanf("%d", &n);

    insertc(str, c, n);

    printf("插入后的字符串为：%s\n", str);

    return 0;
}