c++ 字符串工具类

#include <string>
#include "util.h"

namespace strtool{

std::string trim(const std::string& str) {
    std::string::size_type pos = str.find_first_not_of(' ');
    if (pos == std::string::npos) {
        return str;
    }
    std::string::size_type pos2 = str.find_last_not_of(' ');
    if (pos2 != std::string::npos) {
        return str.substr(pos, pos2 - pos + );
    }
    return str.substr(pos);
}

void split(const std::string& str, std::string sep, std::vector<std::string>& ret) {
    if (str.empty()) {
        return;
    }

    std::string tmp;
    std::string::size_type pos_begin = str.find_first_not_of(sep);
    std::string::size_type comma_pos = ;

    while (pos_begin != std::string::npos) {
        comma_pos = str.find(sep, pos_begin);
        if (comma_pos != std::string::npos) {
            tmp = str.substr(pos_begin, comma_pos - pos_begin);
            pos_begin = comma_pos + sep.length();
        }
        else{
            tmp = str.substr(pos_begin);
            pos_begin = comma_pos;
        }

        if (!tmp.empty()){
            ret.push_back(tmp);
            tmp.clear();
        }
    }
    return;
}

std::string replace(const std::string& str, const std::string& src, const std::string& dest) {
    std::string ret;
    std::string::size_type pos_begin = ;
    std::string::size_type pos  = str.find(src);
    while (pos != std::string::npos) {
        ret.append(str.data() + pos_begin, pos - pos_begin);
        ret += dest;
        pos_begin = pos + ;
        pos = str.find(src, pos_begin);
    }
    if (pos_begin < str.length()) {
        ret.append(str.begin() + pos_begin, str.end());
    }
    return ret;
}

} // namespace strtool

#include <vector> //std::vector

namespace strtool{

std::string trim(const std::string& str);

void split(const std::string& str, std::string sep, std::vector<std::string>& ret);

std::string replace(const std::string& str, const std::string& src, const std::string& dest);

} // namespace strtool

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

void split(const std::string& str, std::string sep, std::vector<std::string>& ret) {
    if (str.empty()) {
        return;
    }
    std::string tmp;
    std::string::size_type pos_begin = str.find_first_not_of(sep);
    std::string::size_type comma_pos = ;

    while (pos_begin != std::string::npos) {
        comma_pos = str.find(sep, pos_begin);
        if (comma_pos != std::string::npos) {
            tmp = str.substr(pos_begin, comma_pos - pos_begin);
            pos_begin = comma_pos + sep.length();
        }
        else{
            tmp = str.substr(pos_begin);
            pos_begin = comma_pos;
        }

        if (!tmp.empty()){
            ret.push_back(tmp);
            tmp.clear();
        }
    }
    return;
}

int main(void) {
    std::string line = "a\tb\tc\td";
    std::string sep = "\t";
    std::vector<std::string> tokens;
    split(line, sep, tokens);
    int len = tokens.size();
    for (int i = ; i < len; i++){
        std::cout << tokens[i] << std::endl;
    }
}