Why is this a warning? I think there are many cases when is more clear to use multi-char int constants instead of "no meaning" numbers or instead of defining const variables with same value. When parsing wave/tiff/other file types is more clear to compare the read values with some 'EVAW', 'data', etc instead of their corresponding values.
Sample code:
int waveHeader = 'EVAW';
Why does this give a warning?
According to the standard (§6.4.4.4/10)
The value of an integer character constant containing more than one character (e.g., 'ab'), [...] is implementation-defined.
long x = '\xde\xad\xbe\xef'; // yes, single quotes
This is valid ISO 9899:2011 C. It compiles without warning under gcc
with -Wall
, and a “multi-character character constant” warning with -pedantic
.
From Wikipedia:
Multi-character constants (e.g. 'xy') are valid, although rarely useful — they let one store several characters in an integer (e.g. 4 ASCII characters can fit in a 32-bit integer, 8 in a 64-bit one). Since the order in which the characters are packed into one int is not specified, portable use of multi-character constants is difficult.
For portability sake, don't use multi-character constants with integral types.