C++ 删除 std::string 中的空格
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remove whitespace in std::string
提问by Mr. Smith
In C++, what's an easy way to turn:
在 C++ 中，有什么简单的方法可以转换：
This std::string
这个 std::string
\t\tHELLO WORLD\r\nHELLO\t\nWORLD \t
Into:
进入：
HELLOWORLDHELLOWORLD
回答by CashCow
Simple combination of std::remove_ifand std::string::erase.
的简单组合std::remove_if和std::string::erase。
Not totally safe version
不是完全安全的版本
s.erase( std::remove_if( s.begin(), s.end(), ::isspace ), s.end() );
For safer version replace ::isspacewith
为了更安全的版本替换::isspace为
std::bind( std::isspace<char>, _1, std::locale::classic() )
(Include all relevant headers)
（包括所有相关标题）
For a version that works with alternative character types replace <char>with <ElementType>or whatever your templated character type is. You can of course also replace the locale with a different one. If you do that, beware to avoid the inefficiency of recreating the locale facet too many times.
对于使用替代字符类型的版本，请替换<char>为<ElementType>您的模板化字符类型。您当然也可以用不同的语言环境替换语言环境。如果这样做，请注意避免多次重新创建语言环境方面的低效率。
In C++11 you can make the safer version into a lambda with:
在 C++11 中，您可以使用以下命令将更安全的版本转换为 lambda：
[]( char ch ) { return std::isspace<char>( ch, std::locale::classic() ); }
回答by billz
If C++03
如果 C++03
struct RemoveDelimiter
{
bool operator()(char c)
{
return (c =='\r' || c =='\t' || c == ' ' || c == '\n');
}
};
std::string s("\t\tHELLO WORLD\r\nHELLO\t\nWORLD \t");
s.erase( std::remove_if( s.begin(), s.end(), RemoveDelimiter()), s.end());
Or use C++11 lambda
或者使用 C++11 lambda
s.erase(std::remove_if( s.begin(), s.end(),
[](char c){ return (c =='\r' || c =='\t' || c == ' ' || c == '\n');}), s.end() );
PS. Erase-remove idiomis used
附注。擦除remove惯用法使用
回答by locojay
c++11
C++11
std::string input = "\t\tHELLO WORLD\r\nHELLO\t\nWORLD \t";
auto rs = std::regex_replace(input,std::regex("\s+"), "");
std::cout << rs << std::endl;
/tmp ??? ./play
/tmp ？？？。/玩
HELLOWORLDHELLOWORLD
回答by pje
In C++11 you can use a lambda rather than using std::bind:
在 C++11 中，您可以使用 lambda 而不是使用 std::bind：
str.erase(
std::remove_if(str.begin(), str.end(),
[](char c) -> bool
{
return std::isspace<char>(c, std::locale::classic());
}),
str.end());
回答by TemplateRex
You could use Boost.Algorithm's erase_all
你可以使用Boost.Algorithm的erase_all
#include <boost/algorithm/string/erase.hpp>
#include <iostream>
#include <string>
int main()
{
std::string s = "Hello World!";
// or the more expensive one-liner in case your string is const
// std::cout << boost::algorithm::erase_all_copy(s, " ") << "\n";
boost::algorithm::erase_all(s, " ");
std::cout << s << "\n";
}
NOTE: as is mentioned in the comments: trim_copy(or its cousins trim_copy_leftand trim_copy_right) only remove whitespace from the beginning and end of a string.
注意：正如评论中提到的：（trim_copy或其表亲trim_copy_left和trim_copy_right）仅从字符串的开头和结尾删除空格。
回答by SelectricSimian
Stepping through it character by character and using string::erase()should work fine.
逐个字符地遍历它并使用它string::erase()应该可以正常工作。
void removeWhitespace(std::string& str) {
for (size_t i = 0; i < str.length(); i++) {
if (str[i] == ' ' || str[i] == '\n' || str[i] == '\t') {
str.erase(i, 1);
i--;
}
}
}
