为什么在c ++中没有if（“Maya”==“Maya”）true？ [英] Why isn't if ("Maya" == "Maya") true in c++?

问题描述

为什么我得到这个代码的结果是Maya不是Maya？

  if（Maya ==Maya）
 printf（Maya is Maya \\\
）; 
 else 
 printf（Maya is not Maya \\\
）; 
  

解决方案

因为你实际上是比较两个指针。以下代替：

  if（std :: string（Maya）==Maya）{/ * ... * /} 
 if（std :: strcmp（Maya，Maya）== 0）{/ * ... * /} 
  / pre> 
 
 
这是因为C ++ 03，§2.13.4说：
 
 
一个普通的字符串文字具有 n 类型的数组 const char 
 $ b $             http://stackoverflow.com/questions/2985532/overloading-operator-to-compare-two-char-using-a-string-comparison\">此问题您为什么不能提供超载 == 对于这种情况。
 
Any idea why I get "Maya is not Maya" as a result for this code?
if ("Maya" == "Maya") 
   printf("Maya is Maya \n");
else
   printf("Maya is not Maya \n");

解决方案
Because you are actually comparing two pointers - use e.g. one of the following instead:
if (std::string("Maya") == "Maya") { /* ... */ } 
if (std::strcmp("Maya", "Maya") == 0) { /* ... */ }
This is because C++03, §2.13.4 says:

  
An ordinary string literal has type "array of n const char"
... and in your case a conversion to pointer applies.

See also this question on why you can't provide an overload for == for this case.

                        
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