Why Are Multi-Character Constants in C Dangerous?

The Perils of Multi-Character Constants

In C , multi-character constants, such as 'EVAW', are valid but often unnecessary and potentially perilous. The C standard does not specify the order in which characters are packed into an integer, making their portability questionable.

The Issue with Multi-Character Constants

The compiler generates a warning when using multi-character constants because, as per the C 14 standard, the value of such a constant is implementation-defined. This means that different compilers or even different versions of the same compiler may interpret 'EVAW' differently, leading to inconsistent results.

Alternatives to Multi-Character Constants

Instead of using multi-character constants, consider the following alternatives:

• Define "no meaning" constants with unique values, such as:

const int WAVE_HEADER = 0x45564157;

• Define enumerated types (enums) to represent different values:

enum WaveHeaderType { EVAW };

• Use string literals to store text strings:

const char* waveHeader = "EVAW";

Portability Considerations

To ensure portability, avoid using multi-character constants with integral types. Stick to the alternatives mentioned above to maintain consistency and avoid unexpected behavior across different platforms.

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