Compiler Warning (level 4) C4201


The new home for Visual Studio documentation is Visual Studio 2017 Documentation on

The latest version of this topic can be found at Compiler Warning (level 4) C4201.

nonstandard extension used : nameless struct/union

Under Microsoft extensions (/Ze), you can specify a structure without a declarator as members of another structure or union. These structures generate an error under ANSI compatibility (/Za).

// C4201.cpp  
// compile with: /W4  
struct S  
   float y;  
      int a, b, c;  // C4201  
} *p_s;  
int main()