Some types are not very well suited for use in a bit-field, because their behavior is implementation-defined. When defining a bit-field, you should
stick to the following safe and portable types:
- In C:
signed short, unsigned short, signed char, unsigned char, signed int,
unsigned int or _Bool
- In C++ before C++14: all enumerated types, as well as
signed short, unsigned short, signed char,
unsigned char, signed int, unsigned int, signed long, unsigned long, signed
long long, unsigned long long or bool
- In C++ starting at C++14: all enumerated and integral types
Noncompliant code example
// Assuming we are in C
int b:3; // Noncompliant - may have the range of values 0..7 or -4..3
Compliant solution
unsigned int b:3;
