使用标准库将循环替换为 strtok

下面是拆分分隔字符串的两个示例。

第一种将std::getline与字符串流一起使用，指定分隔符而不是使用默认换行符。 此技术只能使用单字符分隔符。

第二个示例使用 <regex> 库，该库允许任意长度的分隔符，还可以更好地控制如何识别分隔符。 请注意，点字符必须在正则表达式规范中进行转义，因为在正则表达式语言中，"." 充当通配符。

#include <iostream>
#include <sstream>
#include <vector>
#include <regex>
std::vector<std::string> GetlineSplit(std::string const& line) {
    static const char sep = '.';
    std::istringstream liness{line};
    std::vector<std::string> fields;
    for(std::string field; std::getline(liness, field, sep); ) {
        fields.push_back(field);
    }
    return fields;
}
std::vector<std::string> RegexSplit(std::string const& line) {
    std::regex seps("\."); // the dot character needs to be escaped in a regex
    std::sregex_token_iterator rit(line.begin(), line.end(), seps, -1);
    return std::vector<std::string>(rit, std::sregex_token_iterator());
}
int main() {
    std::string line = "abc.def.ghi.klm.nop.qrs.tuv.wxyz";
    std::cout << "getline split result:n";
    auto fields_getline = GetlineSplit(line);
    for(const auto& field : fields_getline) {
        std::cout << field << 'n';
    }
    std::cout << "nregex split result:n";
    auto fields_regex = RegexSplit(line);
    for(const auto& field : fields_regex) {
        std::cout << field << 'n';
    }
}

我有一个只有静态方法的实用程序类，因为您无法创建此实用程序类的实例。我将其用于处理字符串的各种方法，从转换到删除空格、拆分、更改大小写等。下面是一个从此类中拆分字符串的函数：

实用性.h

class Utility {
public:
    static std::vector<std::string> splitString( const std::string& strStringToSplit, 
                                                 const std::string& strDelimiter, 
                                                 const bool keepEmpty = true );
private:
    Utility();
};

效用.cpp

#include "Utility.h"
// splitString()
std::vector<std::string> Utility::splitString( const std::string& strStringToSplit, 
                                               const std::string& strDelimiter, 
                                               const bool keepEmpty ) {
    std::vector<std::string> vResult;
    if ( strDelimiter.empty() ) {
        vResult.push_back( strStringToSplit );
        return vResult;
    }
    std::string::const_iterator itSubStrStart = strStringToSplit.begin(), itSubStrEnd;
    while ( true ) {
        itSubStrEnd = search( itSubStrStart, strStringToSplit.end(), strDelimiter.begin(), strDelimiter.end() );
        std::string strTemp( itSubStrStart, itSubStrEnd );
        if ( keepEmpty || !strTemp.empty() ) {
            vResult.push_back( strTemp );
        }
        if ( itSubStrEnd == strStringToSplit.end() ) {
            break;
        }
        itSubStrStart = itSubStrEnd + strDelimiter.size();
    }
    return vResult;
} // splitString

此实用程序方法工作所需的库包括<vector>、<string>和<algorithm>，它们在几乎所有应用程序中都常用。

要使用这个函数，我们可以做一个简单的测试，如下所示：

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include "Utility.h"
int main() {
    std::string someLongString2( "Hello World How Are You" );
    std::vector<std::string> singleWords;
    singleWords = Utility::splitString( someLongString, " " );
     // Space is the delimiter and now each individual word 
     // from the long string are now each a new string stored 
     // in this vector. You can use any character for your delimiter.
     // Also this function is not limited to having a single character
     // as its delimiter. You can use a series of characters or specific
     // words as your delimiter. Such as a comma followed by a space.
      std::string someLongString2( "Hello, World, How, Are, You" );
      singleWords.clear();
      singleWords = Utility::splitString( someLongString2, ", " );
    return 0;
} // main

下面是使用标准库替换strtok的解决方案(使用收到的答案(：

std::vector<std::string> SplitLine(std::string const& line, std::string seps)
{
    std::regex regxSeps(seps); // the dot character needs to be escaped in a regex
    std::sregex_token_iterator rit(line.begin(), line.end(), regxSeps, -1);
    return std::vector<std::string>(rit, std::sregex_token_iterator());
}
static int ParseLine(std::string line, std::string seps, size_t startIdx, std::vector<CNode>& collection)
{
    if (startIdx > collection.size())
    {
        throw std::invalid_argument("the start index is out of range");
    }
    auto objectTypes = SplitLine(line, seps);
    auto idx = startIdx;
    for (const auto& objectType : objectTypes)
    {
        if (idx == collection.size())
        {
            collection.push_back(CNode(idx));
        }
        collection[idx++].SetObjectType(objectType);
    }
    return (idx - 1);
}
int main()
{
    std::string seps = "\."; // the dot character needs to be escaped in a regex
    ...
}