Compiler Warning (levels 2 and 4) C4200
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The latest version of this topic can be found at Compiler Warning (levels 2 and 4) C4200.
nonstandard extension used : zero-sized array in struct/union
Indicates that a structure or union contains an array that has zero size.
Declaration of a zero-sized array is a Microsoft extension. This causes a Level-2 warning when a C++ file is compiled and a Level-4 warning when a C file is compiled. C++ compilation also gives this warning: "Cannot generate copy-ctor or copy-assignment operator when UDT contains a zero-sized array." This example generates warning C4200:
// C4200.cpp // compile by using: cl /W4 c4200.cpp struct A { int a[0]; // C4200 }; int main() { }
This non-standard extension is often used to interface code with external data structures that have a variable length. If this scenario applies to your code, you can disable the warning:
// C4200b.cpp // compile by using: cl /W4 c4200a.cpp #pragma warning(disable : 4200) struct A { int a[0]; }; int main() { }