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

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。

其他回答

下面是一个示例标记器类,它可以实现您想要的功能

//Header file
class Tokenizer 
{
    public:
        static const std::string DELIMITERS;
        Tokenizer(const std::string& str);
        Tokenizer(const std::string& str, const std::string& delimiters);
        bool NextToken();
        bool NextToken(const std::string& delimiters);
        const std::string GetToken() const;
        void Reset();
    protected:
        size_t m_offset;
        const std::string m_string;
        std::string m_token;
        std::string m_delimiters;
};

//CPP file
const std::string Tokenizer::DELIMITERS(" \t\n\r");

Tokenizer::Tokenizer(const std::string& s) :
    m_string(s), 
    m_offset(0), 
    m_delimiters(DELIMITERS) {}

Tokenizer::Tokenizer(const std::string& s, const std::string& delimiters) :
    m_string(s), 
    m_offset(0), 
    m_delimiters(delimiters) {}

bool Tokenizer::NextToken() 
{
    return NextToken(m_delimiters);
}

bool Tokenizer::NextToken(const std::string& delimiters) 
{
    size_t i = m_string.find_first_not_of(delimiters, m_offset);
    if (std::string::npos == i) 
    {
        m_offset = m_string.length();
        return false;
    }

    size_t j = m_string.find_first_of(delimiters, i);
    if (std::string::npos == j) 
    {
        m_token = m_string.substr(i);
        m_offset = m_string.length();
        return true;
    }

    m_token = m_string.substr(i, j - i);
    m_offset = j;
    return true;
}

例子:

std::vector <std::string> v;
Tokenizer s("split this string", " ");
while (s.NextToken())
{
    v.push_back(s.GetToken());
}

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。

这里有许多过于复杂的建议。试试这个简单的std::string解决方案:

using namespace std;

string someText = ...

string::size_type tokenOff = 0, sepOff = tokenOff;
while (sepOff != string::npos)
{
    sepOff = someText.find(' ', sepOff);
    string::size_type tokenLen = (sepOff == string::npos) ? sepOff : sepOff++ - tokenOff;
    string token = someText.substr(tokenOff, tokenLen);
    if (!token.empty())
        /* do something with token */;
    tokenOff = sepOff;
}

Boost标记器类可以使这类事情变得非常简单:

#include <iostream>
#include <string>
#include <boost/foreach.hpp>
#include <boost/tokenizer.hpp>

using namespace std;
using namespace boost;

int main(int, char**)
{
    string text = "token, test   string";

    char_separator<char> sep(", ");
    tokenizer< char_separator<char> > tokens(text, sep);
    BOOST_FOREACH (const string& t, tokens) {
        cout << t << "." << endl;
    }
}

针对c++ 11更新:

#include <iostream>
#include <string>
#include <boost/tokenizer.hpp>

using namespace std;
using namespace boost;

int main(int, char**)
{
    string text = "token, test   string";

    char_separator<char> sep(", ");
    tokenizer<char_separator<char>> tokens(text, sep);
    for (const auto& t : tokens) {
        cout << t << "." << endl;
    }
}

下面是我的Swiss®军刀字符串标记器,用于用空格分隔字符串,处理单引号和双引号包装的字符串,以及从结果中剥离这些字符。我使用RegexBuddy 4。x生成大部分代码片段,但我添加了用于剥离引号和其他一些东西的自定义处理。

#include <string>
#include <locale>
#include <regex>

std::vector<std::wstring> tokenize_string(std::wstring string_to_tokenize) {
    std::vector<std::wstring> tokens;

    std::wregex re(LR"(("[^"]*"|'[^']*'|[^"' ]+))", std::regex_constants::collate);

    std::wsregex_iterator next( string_to_tokenize.begin(),
                                string_to_tokenize.end(),
                                re,
                                std::regex_constants::match_not_null );

    std::wsregex_iterator end;
    const wchar_t single_quote = L'\'';
    const wchar_t double_quote = L'\"';
    while ( next != end ) {
        std::wsmatch match = *next;
        const std::wstring token = match.str( 0 );
        next++;

        if (token.length() > 2 && (token.front() == double_quote || token.front() == single_quote))
            tokens.emplace_back( std::wstring(token.begin()+1, token.begin()+token.length()-1) );
        else
            tokens.emplace_back(token);
    }
    return tokens;
}