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| author | Adam Bard <github@adambard.com> | 2017-09-12 22:42:18 -0700 |
|---|---|---|
| committer | GitHub <noreply@github.com> | 2017-09-12 22:42:18 -0700 |
| commit | a5c23e8af4be114ed5e04c1034acbc6ef4890719 (patch) | |
| tree | 87cf0e0cadeefbe09fbf39d2dab9f5f25bc71273 /c.html.markdown | |
| parent | a6e460618dad10b5962dbd496f8826902fab6eae (diff) | |
Update c.html.markdown
Note on macro hygiene. Fixes #2853
Diffstat (limited to 'c.html.markdown')
| -rw-r--r-- | c.html.markdown | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/c.html.markdown b/c.html.markdown index 1ad0dd53..c47a2df7 100644 --- a/c.html.markdown +++ b/c.html.markdown @@ -756,8 +756,14 @@ as the C file. /* Like c source files macros can be defined in headers and used in files */ /* that include this header file. */ #define EXAMPLE_NAME "Dennis Ritchie" -/* Function macros can also be defined. */ -#define ADD(a, b) (a + b) + +/* Function macros can also be defined. */ +#define ADD(a, b) ((a) + (b)) + +/* Notice the parenthesis surrounding the arguments -- this is important to */ +/* ensure that a and b don't get expanded in an unexpected way (e.g. consider */ +/* MUL(x, y) (x * y); MUL(1 + 2, 3) would expand to (1 + 2 * 3), yielding an */ +/* incorrect result) */ /* Structs and typedefs can be used for consistency between files. */ typedef struct Node |