扩展c ++字符串成员函数 [英] extending c++ string member functions

问题描述

我有一个需要做一个不区分大小写的find，并发现了下面的代码，这是做的

  bool ci_equal ch1，char ch2）
 {
 return toupper（（unsigned char）ch1）== toupper（（unsigned char）ch2）; 
} 
 
 size_t ci_find（const string& str1，const string& str2）
 {
 string :: const_iterator pos = std :: search（str1。begin ），str1。end（），str2。
 begin（），str2。end（），ci_equal）; 
 if（pos == str1。end（））
 return string :: npos; 
 else 
 return pos  -  str1。开始 （ ）; 
} 
  

这让我想知道什么会使它成为一个成员函数'string'，因此可以这样调用：

  string S =abcdefghijklmnopqrstuv; 
 string F =GHI; 
 
 S.ci_find（F）; 
  

我意识到在非英语语言中的case转换有很多问题，但这不是问题有兴趣。

作为一个新手，我很快就迷失在容器和模板中。

反正要做到这一点？

解决方案

std :: string 不会被扩展。

你可以将std :: string封装到你的类中，并在该类中设置那些成员函数。

I had a need to do a case insensitive find and found the following code which did the trick

bool ci_equal(char ch1, char ch2)
{
    return toupper((unsigned char)ch1) == toupper((unsigned char)ch2);
}

size_t ci_find(const string& str1, const string& str2)
{
    string::const_iterator pos = std::search(str1. begin ( ), str1. end ( ), str2.
    begin ( ), str2. end ( ), ci_equal);
    if (pos == str1. end ( ))
        return string::npos;
    else
        return pos - str1. begin ( );
}

That got me to wondering what it would take to make this a member function of 'string' so it could be called like this:

string S="abcdefghijklmnopqrstuv";
string F="GHI";

S.ci_find(F);

I realize that there are many problems with case conversions in non-English languages but that's not the question I'm interested in.

Being a neophyte, I quickly got lost among containers and templates.

Is there anyway to do this? Could someone point to me an example of something similar?

解决方案

std::string is not made to be extended.

You could encapsulate an std::string into a class of yours and set those member functions in that class.

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