...
This CUBE() macro definition is non-compliant because it fails to parethesize parenthesize the variable names.
| Code Block |
|---|
#define CUBE(I) (I * I * I) int a = 81 / CUBE(2 + 1); |
...
| Code Block |
|---|
int a = 81 / (2 + 1 * 2 + 1 * 2 + 1); /* evalutaesevaluates to 11 */ |
while the desired behavior is
...
| Code Block |
|---|
#define CUBE(I) ( (I) * (I) * (I) )
int a = 81 / CUBE(2 + 1);
|
However, if a parameter appears several times in the expansion, the macro may not work properly if the actual argument is an expression with side effects. Given the CUBE() macro above, the invocation:
...
| Code Block |
|---|
int a = 81 / (i++ * i++ * i++);
|
| Wiki Markup |
|---|
which is undefined (see \[[EXP30|EXP30-C. Do not depend on order of evaluation between sequence points]\]). |
...