Compiler Warning (level 4) C4431
missing type specifier - int assumed. Note: C no longer supports default-int
This error can be generated as a result of compiler conformance work that was done for Visual C++ 2005: Visual C++ no longer creates untyped identifiers as int by default. The type of an identifier must be specified explicitly. See Breaking Changes in the Visual C++ 2005 Compiler for more information.
This warning is off by default. See Compiler Warnings That Are Off by Default for more information.
Example
The following sample generates C4431.
// C4431.c
// compile with: /c /W4
#pragma warning(default:4431)
i; // C4431
int i; // OK