数组的基本操作：批量增加元素

#include<stdio.h>
#include<string.h>
#define maxsize 5
int func(int arr1[], int len1, int arr2[], int len2, int index) {
//先判断边界条件
	if (len1 + len2 > maxsize)
		return -1;
	if (index > len1)
		return -1;
	//为arr2先空出位置
	for (int i = len1 - 1; i >= index; i--)
		arr1[i + len2] = arr1[i];
	//插入len2的所有元素
	for (int i = 0; i < len2; i++)
		arr1[i + index] = arr2[i];
	len1 += len2;
	return len1;
}
int main() {
	int arr1[maxsize] = { 1,2,3 };
	int len1 = 3;
	int arr2[maxsize] = { 4,5 };
	int len2 = 2;
	int index = 3;
	len1 = func(arr1, len1, arr2, len2, index);
	for (int i = 0; i < len1; i++)
		printf("%d", arr1[i]);//依次打印该数组的所有元素
	return 0;
}