There are three distinct char types, (plain) char, signed char and unsigned char. signed
char and unsigned char should only be used for numeric data, and plain char should only be used for character data.
Since it is implementation-defined, the signedness of the plain char type should not be assumed.
Noncompliant code example
signed char a = 'a'; // Noncompliant, explicitly signed
unsigned char b = '\r'; // Noncompliant, explicitly unsigned
char c = 10; // Noncompliant
unsigned char d = c; // Noncompliant, d is explicitly signed while c is not
char e = a; // Noncompliant, a is explicitly signed while e is not
Compliant solution
char a = 'a';
char b = '\r';
unsigned char c = 10;
signed char c = 10;
Exceptions
- Since the integer value 0 is used as a sentinel for the end of a string, converting this value to char is ignored.
