c++ - VS2010 C代码——字符串池

Question

当您使用以下标志编译时，下面的代码在 VS 2010 中崩溃，如果您添加/GF- 或删除优化标志，它们不会崩溃。崩溃发生在翻译 'if( path[i] == '/' )' 的汇编代码处。我喜欢了解编译器在这里所​​做的优化并导致崩溃。期待一些指点。

-卡尔提克

cl.exe/MD/O2 test.c

// 测试.c

#include <stdio.h>

#include  <string.h>

void testpath(char* path, int bufsiz)  
{  

    int i;  

    printf("%p\n", path);  
    for( i=0; i < strlen(path); i++ ) {  
      if( path[i] == '/' ) {  
         path[i] = '\\';  
     }  
  }  
}

int main()  
{  

    const char* path = "testexport.prj";  
    char *path1 = "testexport.prj";  
    printf("%p\n", path);  
    printf("%p\n", path1);  
    testpath(path, 1024);  
}  

Answer 1

尝试修改字符串文字的内容会调用未定义的行为。

来自 ISO C99(第 6.4.5/6 节)

It is unspecified whether these arrays are distinct provided their elements have the appropriate values. If the program attempts to modify such an array, the behavior is undefined

来自 ISO C++-98(2.13.4/2 节)

Whether all string literals are distinct(that is, are stored in non overlapping objects) is implementation defined. The effect of attempting to modify a string literal is undefined.

在大多数实现(包括 MSVC)上，这会导致您的应用程序崩溃。