Java有一个方便的分割方法:

String str = "The quick brown fox";
String[] results = str.split(" ");

在c++中有简单的方法来做到这一点吗?


当前回答

我贴出了类似问题的答案。 不要白费力气。我使用过许多库,我遇到过的最快、最灵活的库是:c++ String Toolkit Library。

这里有一个如何使用它的例子,我已经张贴在stackoverflow的其他地方。

#include <iostream>
#include <vector>
#include <string>
#include <strtk.hpp>

const char *whitespace  = " \t\r\n\f";
const char *whitespace_and_punctuation  = " \t\r\n\f;,=";

int main()
{
    {   // normal parsing of a string into a vector of strings
       std::string s("Somewhere down the road");
       std::vector<std::string> result;
       if( strtk::parse( s, whitespace, result ) )
       {
           for(size_t i = 0; i < result.size(); ++i )
            std::cout << result[i] << std::endl;
       }
    }

    {  // parsing a string into a vector of floats with other separators
       // besides spaces

       std::string s("3.0, 3.14; 4.0");
       std::vector<float> values;
       if( strtk::parse( s, whitespace_and_punctuation, values ) )
       {
           for(size_t i = 0; i < values.size(); ++i )
            std::cout << values[i] << std::endl;
       }
    }

    {  // parsing a string into specific variables

       std::string s("angle = 45; radius = 9.9");
       std::string w1, w2;
       float v1, v2;
       if( strtk::parse( s, whitespace_and_punctuation, w1, v1, w2, v2) )
       {
           std::cout << "word " << w1 << ", value " << v1 << std::endl;
           std::cout << "word " << w2 << ", value " << v2 << std::endl;
       }
    }

    return 0;
}

其他回答

对于简单的事情,我只使用以下方法:

unsigned TokenizeString(const std::string& i_source,
                        const std::string& i_seperators,
                        bool i_discard_empty_tokens,
                        std::vector<std::string>& o_tokens)
{
    unsigned prev_pos = 0;
    unsigned pos = 0;
    unsigned number_of_tokens = 0;
    o_tokens.clear();
    pos = i_source.find_first_of(i_seperators, pos);
    while (pos != std::string::npos)
    {
        std::string token = i_source.substr(prev_pos, pos - prev_pos);
        if (!i_discard_empty_tokens || token != "")
        {
            o_tokens.push_back(i_source.substr(prev_pos, pos - prev_pos));
            number_of_tokens++;
        }

        pos++;
        prev_pos = pos;
        pos = i_source.find_first_of(i_seperators, pos);
    }

    if (prev_pos < i_source.length())
    {
        o_tokens.push_back(i_source.substr(prev_pos));
        number_of_tokens++;
    }

    return number_of_tokens;
}

懦弱的免责声明:我编写实时数据处理软件,其中数据通过二进制文件、套接字或一些API调用(I/O卡、摄像头)传入。除了在启动时读取外部配置文件以外,我从未将这个函数用于更复杂或时间要求更严格的事情。

我认为这就是字符串流上的>>操作符的用途:

string word; sin >> word;

这是一个简单的stl解决方案(~5行!)使用std::find和std::find_first_not_of来处理重复的分隔符(例如空格或句号),以及开头和结尾的分隔符:

#include <string>
#include <vector>

void tokenize(std::string str, std::vector<string> &token_v){
    size_t start = str.find_first_not_of(DELIMITER), end=start;

    while (start != std::string::npos){
        // Find next occurence of delimiter
        end = str.find(DELIMITER, start);
        // Push back the token found into vector
        token_v.push_back(str.substr(start, end-start));
        // Skip all occurences of the delimiter to find new start
        start = str.find_first_not_of(DELIMITER, end);
    }
}

现场试试吧!

简单的c++代码(标准c++ 98),接受多个分隔符(在std::string中指定),只使用向量、字符串和迭代器。

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

std::vector<std::string> 
split(const std::string& str, const std::string& delim){
    std::vector<std::string> result;
    if (str.empty())
        throw std::runtime_error("Can not tokenize an empty string!");
    std::string::const_iterator begin, str_it;
    begin = str_it = str.begin(); 
    do {
        while (delim.find(*str_it) == std::string::npos && str_it != str.end())
            str_it++; // find the position of the first delimiter in str
        std::string token = std::string(begin, str_it); // grab the token
        if (!token.empty()) // empty token only when str starts with a delimiter
            result.push_back(token); // push the token into a vector<string>
        while (delim.find(*str_it) != std::string::npos && str_it != str.end())
            str_it++; // ignore the additional consecutive delimiters
        begin = str_it; // process the remaining tokens
        } while (str_it != str.end());
    return result;
}

int main() {
    std::string test_string = ".this is.a.../.simple;;test;;;END";
    std::string delim = "; ./"; // string containing the delimiters
    std::vector<std::string> tokens = split(test_string, delim);           
    for (std::vector<std::string>::const_iterator it = tokens.begin(); 
        it != tokens.end(); it++)
            std::cout << *it << std::endl;
}

这是一个非常简单的问题:

#include <vector>
#include <string>
using namespace std;

vector<string> split(const char *str, char c = ' ')
{
    vector<string> result;

    do
    {
        const char *begin = str;

        while(*str != c && *str)
            str++;

        result.push_back(string(begin, str));
    } while (0 != *str++);

    return result;
}