C++标准库没有string的分割函数，只能用C语言split函数，感觉不太方便。我们用stringstream实现一个简单的split函数：
void split(const string &str, vector<string> &vec, const char &c)
{
stringstream ss(str);
string sub;
while (getline(ss, sub, c))
{
vec.push_back(sub);
}
}
此实现代码固然简单，但出现多个连续的分隔符时不太符合我们的要求。没办法，我们还是用最原始的方法做吧。
void split(const string &str, vector<string> &vec, const char &c)
{
string::size_type pos1 = 0;
string::size_type pos2 = str.find(c, pos1);
while(pos2 != string::npos)
{
vec.push_back(str.substr(pos1, pos2-pos1));
pos1 = pos2 + sizeof(c);
pos2 = str.find(c, pos1);
}
if(pos1 != str.length())
{
vec.push_back(str.substr(pos1));
}
}
测试代码
#include <iostream>
#include <sstream>
#include <vector>
using namespace std;
void split(const string &str, vector<string> &vec, const char &c)
{
string::size_type pos1 = 0;
string::size_type pos2 = str.find(c, pos1);
while(pos2 != string::npos)
{
vec.push_back(str.substr(pos1, pos2-pos1));
pos1 = pos2 + sizeof(c);
pos2 = str.find(c, pos1);
}
if(pos1 != str.length())
{
vec.push_back(str.substr(pos1));
}
}
/*
void split(const string &str, vector<string> &vec, const char &c)
{
stringstream ss(str);
string sub;
while (getline(ss, sub, c))
{
vec.push_back(sub);
}
}
*/
void print_vec(vector<string> &vec)
{
for(auto p = vec.begin(); p != vec.end(); p++)
cout << *p << endl;
}
int main(void)
{
vector<string> vec;
string str1 = "hello world";
string str2 = " hello world";
string str3 = "hello world ";
string str4 = " hello world ";
string str5 = " hello world ";
cout << "[" << str1 << "]" << endl;
vec.clear();
split(str1, vec, ' ');
cout << "----------begin----------" << endl;
print_vec(vec);
cout << "-----------end-----------" << endl;
cout << "[" << str2 << "]" << endl;
vec.clear();
split(str2, vec, ' ');
cout << "----------begin----------" << endl;
print_vec(vec);
cout << "-----------end-----------" << endl;
cout << "[" << str3 << "]" << endl;
vec.clear();
split(str3, vec, ' ');
cout << "----------begin----------" << endl;
print_vec(vec);
cout << "-----------end-----------" << endl;
cout << "[" << str4 << "]" << endl;
vec.clear();
split(str4, vec, ' ');
cout << "----------begin----------" << endl;
print_vec(vec);
cout << "-----------end-----------" << endl;
cout << "[" << str5 << "]" << endl;
vec.clear();
split(str5, vec, ' ');
cout << "----------begin----------" << endl;
print_vec(vec);
cout << "-----------end-----------" << endl;
return 0;
}
运行结果
[ycxie@fedora Workspace]$ g++ str_split.cpp -o str_split -Wall [ycxie@fedora Workspace]$ ./str_split [hello world] ----------begin---------- hello world -----------end----------- [ hello world] ----------begin---------- hello world -----------end----------- [hello world ] ----------begin---------- hello world -----------end----------- [ hello world ] ----------begin---------- hello world -----------end----------- [ hello world ] ----------begin---------- hello world -----------end-----------