三个任务

#include<stdio.h>
int getArrSum(int arr[],int len){
	int sum = 0;
	for(int i = 0;i<len;i++){
		sum += arr[i];
	}
	return sum;
}

int getArrMax(int arr[],int len){
	int max = arr[0];
	for(int i = 1;i<len;i++){
		if(arr[i] > max){
			max = arr[i];
		}
	}
	return max;
}

int findArrValue(int arr[],int len,int val){
	for(int i = 0;i<len;i++){
		if(arr[i]==val){
			return i;
		}
	}
	return -1;
}
int main(){
	int arr[]={1,2,3,4,5};
	int len = sizeof(arr) / sizeof(arr[0]);
	printf("数组的和：%d\n",getArrSum(arr,len));
	printf("数组的最大值：%d\n",getArrMax(arr,len));
	int target = 3;
	int index = findArrValue(arr,len,target);
	if(index != -1){
		printf("值%d的下标：%d\n",target,index);
	}else{
		printf("未找到值%d\n",target);
	}
	
}

结果：