c++ - C++ 删除字符串中多余的空格或制表符

Question

我需要从行中删除额外的空格，如1.47\t\t4.32 5.1 \t\tf41.4. 我怎么能用boost做到这一点？

Answer 1

如果您只想轻松地做到这一点，我会使用这样的东西：

std::string single_space(std::string const &input) { 
    std::istringstream buffer(input);
    std::ostringstream result;

    std::copy(std::istream_iterator<std::string>(buffer),
              std::istream_iterator<std::string>(),
              std::ostream_iterator<std::string>(result, " "));
    return result.str();
}

如果您担心让它尽可能快，您可能想看看今天早些时候的另一个问题。

Answer 2

我找到了我的问题的答案。

std::string trim(const std::string& str,
                 const std::string& whitespace = " \t")
{
    const auto strBegin = str.find_first_not_of(whitespace);
    if (strBegin == std::string::npos)
        return ""; // no content

    const auto strEnd = str.find_last_not_of(whitespace);
    const auto strRange = strEnd - strBegin + 1;

    return str.substr(strBegin, strRange);
}

std::string reduce(std::string& str,
                   const std::string& fill = " ",
                   const std::string& whitespace = " \t")
{
    // trim first
    auto result = trim(str, whitespace);
    // replace sub ranges
    auto beginSpace = result.find_first_of(whitespace);
    while (beginSpace != std::string::npos)
    {
        const auto endSpace = result.find_first_not_of(whitespace, beginSpace);
        const auto range = endSpace - beginSpace;

        result.replace(beginSpace, range, fill);

        const auto newStart = beginSpace + fill.length();
        beginSpace = result.find_first_of(whitespace, newStart);
    }

    return result;
}

Answer 3

这是删除多余空格的非常简单的实现。

#include <iostream>
std::string trimExtraWhiteSpaces(std::string &str);
int main(){
    std::string str = "  Apple    is a     fruit   .  ";
    str = trimExtraWhiteSpaces(str);
    std::cout<<str;
}
std::string trimExtraWhiteSpaces(std::string &str){
    std::string s;
    bool first = true;
    bool space = false;
    std::string::iterator iter;
    for(iter = str.begin(); iter != str.end(); ++iter){
        if(*iter == ' '){
            if(first == false){
                space = true;
            }
        }else{
            if(*iter != ',' && *iter != '.'){
                if(space){
                    s.push_back(' ');
                }
            }
            s.push_back(*iter);
            space = false;
            first = false;
        }
    }
    return s;
}