字符串去除前后空格

void trim(string &s){
    if(!s.empty() ){
         s.erase(0, s.find_first_not_of(" "));
         s.erase(s.find_last_not_of(" ") + 1);
     }
}

对map和set进行排序

​​可以将元素项转换为vector的元素,然后排序后输出​​

#include <iostream>
#include <string>
#include <map>
#include <algorithm>
#include <vector>

using namespace std;

bool cmp(pair<string, int> &left, pair<string, int> &right){
    return left.second < right.second;
}

int main(){

    map<string, int> ma;
    ma["Alice"] = 86;
    ma["Bob"] = 78;
    ma["Zip"] = 92;
    ma["Stdevn"] = 88;
    
    vector<pair<string, int> > vec(ma.begin(),ma.end());
    
    sort(vec.begin(),vec.end(),cmp);
    
    for (vector<pair<string, int> >::iterator it = vec.begin(); it != vec.end(); ++it){
    
        cout << it->first << " " << it->second << endl;
    }

    return 0;
}

按某字符分割字符串

#include <vector>
#include<sstream>
#include <string>

using namespace std;

vector<string> split(string src, char c) {

    stringstream temp(src);
    
    string s;
    vector<string> v;

    while (getline(temp, s, c)) {
        v.push_back(s);
    }
    
    return v;
}

字符串数字互转

#include <iostream>
#include <sstream>
#include <string>
using namespace std;

// 数字转字符串
void toString(string &s, int &num){
    stringstream ss;
    ss << num;
    ss >> s;
}

// 字符串转数字
void toInt(string &s, int &num){
    stringstream ss;
    ss << s;
    ss >> num;
}

int main(){
    string s;
    int num = 10;

    toString(s, num);
    cout << s << endl;
    
    s = "999";
    toInt(s, num)
    cout << num << endl;
    
    return 0;
}