c++自带的查找函数详解

#include<iostream>
#include<algorithm>
using namespace std;
int main() {
	/*排好序的*/
	int numList1[5] = { 1,2,3,4,5 };
	int n1 = 2;
	/*乱序的*/
	int numList2[5] = { 1,3,2,4,5 };
	int n2 = 2;
	cout << binary_search(numList1, numList1 + 5, n1) << endl;  //true
	cout << binary_search(numList2, numList2 + 5, n1) << endl;  //false
    //返回值为物理地址，因此要获得对应的逻辑地址，需要减去数组的起始位置。
	cout << lower_bound(numList1, numList1 + 5, n1)- numList1 << endl;  //1
	cout << upper_bound(numList1, numList1 + 5, n1)- numList1 << endl;  //2
	cout << lower_bound(numList2, numList2 + 5, n1)- numList2<< endl;  //1
	cout << upper_bound(numList2, numList2 + 5, n1) - numList2 << endl;  //3
}

/*乱序的*/
	int numList2[5] = { 1,3,2,4,5 };
	int n2 = 2;
	int* pos = find(numList2, numList2 + 5, 2); //若找到，则返回物理地址，需要减去首地址以获得下标
	if (pos == (numList2 + 5)) {
		cout << "Couldn't find it";
	}
	else
		cout << pos - numList2; //返回下标

    string str = "abcd";
	if (find(str.begin(), str.end(), 'a') != str.end())
	//使用迭代器
		cout << "Find it!";
	else
		cout << "Couldn't find it!";
// 或者
    string str = "abcd";
	cout << str.find('a');
	//返回的是下标的值而不是上面的指针或是迭代器