访问冲突写入位置？ [英] Access violation writing location?

问题描述

我想写一个函数来反转一个字符串，但我有这样的异常，当我做：* str ++ = * end;谁知道什么是什么原因？提前致谢。

  void reverse（char * str）
 {
 char * end = str; 
 char temp; 
 if（str）
 {
 while（* end）
 {
 end ++; 
} 
 end--; 
 
 while（str  {
 temp = * str; 
 * str ++ = * end; 
 * end  -  = temp; 
} 
} 
} 
  

解决方案>

机会是，你使用字符串文字调用函数：

  reverse（ablewasiereisawelba）; 
 

您不能修改字符串文字而不调用未定义的行为，崩溃是对尝试的有效响应修改字符串文字。请确保您传递非常量数组：

  char palindrome [] =ablewasiereisawelba 
 reverse（palindrome）; 
  

C ++ 2011标准ISO / IEC 14882：2011说：

2.14.5字符串文字[lex.string]

¶12尝试修改字符串文字是未定义的。

通常，字符串文字放置在只读内存中，尝试修改一个字符串会导致崩溃。这当然是对调用未定义行为的完全合理的响应。

I am trying to write a function to reverse a string, but I got such exception when I am doing: *str++ = *end; anyone who knows what's the reason? Thanks in advance.

void reverse(char* str)
 {
    char *end = str;
    char temp;
    if(str)
    {
      while(*end)
       {
     end++;
       }
    end--;

    while(str<end)
    {
       temp = *str;
       *str++ = *end;
       *end--=temp;
    }
   }
 }

解决方案

Chances are, you called the function with a string literal:

 reverse("ablewasiereisawelba");

You can't modify string literals without invoking undefined behaviour, and crash is a valid response to an attempt to modify a string literal. Make sure you pass a non-constant array instead:

 char palindrome[] = "ablewasiereisawelba";
 reverse(palindrome);

The C++ 2011 standard, ISO/IEC 14882:2011 says:

2.14.5 String literal [lex.string]

¶12 The effect of attempting to modify a string literal is undefined.

Commonly, string literals are placed in readonly memory, and an attempt to modify one leads to a 'crash'. That is certainly a perfectly legitimate response to invoking undefined behaviour.

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