转载自:https://blog.csdn.net/butterfly_dreaming/article/details/10142443#
trim和split在其他语言中都有实现,在C++标准库中没有,下面实现一下:
trim
1.使用string的find_first_not_of,和find_last_not_of方法
#include <iostream>
#include <string>
using namespace std;
string& trim(string &);
int main() {
string a(" ab cd ");
cout<<a<<endl;
cout<<trim(a)<<endl;
return 0;
}
string& trim(string& s){
if(s.empty())return s;
s.erase(0, s.find_first_not_of(' '));
s.erase(s.find_last_not_of(' ') + 1);
return s;
}
2.使用boost库中的trim,boost库对提供很多C++标准库没有但是又非常常用和好用的库函数,例如正则表达式,线程库等等。
#include <iostream>
#include <string>
#include <boost/algorithm/string.hpp>
using namespace std;
using namespace boost;
int main() {
string a(" ab cd ");
cout<<a<<endl;
trim(a);
cout<<a<<endl;
return 0;
}
split
#include <iostream>
#include <string>
#include <vector>
using namespace std;
void split(string&, string&, vector<string>*);
int main() {
string a("ab cd");
vector<string> b;
string c(" ");
cout<<a<<endl;
split(a, c, &b);
cout<<b[1]<<endl;
return 0;
}
void split(string& s, string& delim, vector<string>* ret){
size_t last = 0;
size_t index = s.find_first_of(delim, last);
while(index != string::npos){//查找到匹配
ret->push_back(s.substr(last, index-last));
last = index + 1;
index = s.find_first_of(delim, last);
}
if(index - last > 0)ret->push_back(s.substr(last, index-last));
}