'identifier' : conversion from 'type1' to 'type2', possible loss of data
The types are different. Type conversion may result in loss of data. The compiler makes the type conversion. This warning is off by default.
The following sample generates C4242:
// compile with /W4 #pragma warning(4:4242) int func() { return 0; } void main() { char a; a = func(); // C4242, return type and variable type do not match }