C++常用的string字元串截斷函數

C++中經常會用到標準庫函數庫（STL）的string字元串類，跟其他語言的字元串類相比有所缺陷。這裡就分享下我經常用到的兩個字元串截斷函數：

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

using namespace std;

//根據字元切分string，相容最前最後存在字元
void CutString(string line, vector<string> &subline, char a)
{
    //首字母為a，剔除首字母
    if (line.size() < 1)
    {
        return;
    }
    if (line[0] == a)
    {
        line.erase(0, 1);
    }

    size_t pos = 0;
    while (pos < line.length())
    {
        size_t curpos = pos;
        pos = line.find(a, curpos);
        if (pos == string::npos)
        {
            pos = line.length();
        }
        subline.push_back(line.substr(curpos, pos - curpos));
        pos++;
    }

    return;
}

//根據空截斷字元串
void ChopStringLineEx(string line, vector<string> &substring)
{
    stringstream linestream(line);
    string sub;

    while (linestream >> sub)
    {
        substring.push_back(sub);
    }
}

int main()
{
    string line = ",abc,def,ghi,jkl,mno,";
    vector<string> subline;
    char a = ',';
    CutString(line, subline, a);
    cout << subline.size()<<endl;
    for (auto it : subline)
    {
        cout << it << endl;
    }

    cout << "-----------------------------" << endl;

    line = "   abc   def   ghi  jkl  mno ";
    subline.clear();    
    ChopStringLineEx(line, subline);
    cout << subline.size() << endl;
    for (auto it : subline)
    {
        cout << it << endl;
    }


    return 0;
}

函數CutString根據選定的字元切分string，相容最前最後存在字元；函數ChopStringLineEx根據空截斷字元串。這兩個函數在很多時候都是很實用的，例如在讀取文本的時候，通過getline按行讀取，再用這兩個函數分解成想要的子串。