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C++小细节笔记

news 2025/7/14 19:00:36

1、C++字符串转数字 – 数字转字符串

	//string => int   使用 stoi stol//int => string   使用 to_string()

2、C++遍历

	int evalRPN(vector<string>& tokens) {stack<int> intStack;for(string &str:tokens){}

	bool isValid(string s) {stack<char> cs;for(char ch:s){}

	int arr[10];for (int v : arr){cout << v << "  ";}

3、生成随机数

#include<iostream>
#include<stdlib.h> //包含随机数函数srand
#include<time.h> //需要用time作为随机数种子using namespace std;int main()
{int arr[10];srand(time(NULL));for (int i = 0; i < 10; i++){arr[i] = rand() % 100 + 1;}for (int v : arr){cout << v << "  ";}cout << endl;return 0;
}

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4、查函数

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5、测试排序算法花费时间

int main()
{const int COUNT = 10000;int* arr = new int[COUNT];int* brr = new int[COUNT];int* crr = new int[COUNT];int* drr = new int[COUNT];srand(time(NULL));for (int i = 0; i < COUNT; i++){int val = rand() % COUNT;arr[i] = val;brr[i] = val;crr[i] = val;drr[i] = val;}clock_t begin,end;begin = clock();BubbleSort(arr, COUNT);end = clock();cout << "BubbleSort spend: " << (end - begin) * 1.0 / CLOCKS_PER_SEC << "s" << endl;begin = clock();ChoiceSort(brr, COUNT);end = clock();cout << "ChoiceSort spend: " << (end - begin) * 1.0 / CLOCKS_PER_SEC << "s" << endl;begin = clock();InsertSort(crr, COUNT);end = clock();cout << "InsertSort spend: " << (end - begin) * 1.0 / CLOCKS_PER_SEC << "s" << endl;begin = clock();ShellSort(drr, COUNT);end = clock();cout << "ShellSort spend: " << (end - begin) * 1.0 / CLOCKS_PER_SEC << "s" << endl;}