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int x, y, z, tmp; if (z == 0) tmp = x; x = y; y = tmp; |
Furthermore, this macro violates PRE02-C. Macro replacement lists should be parenthesized.
Noncompliant Code Example
This noncompliant code example parenthesizes its macro arguments, but inadequately bounds multiple statements:
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/*
* Swaps two values and requires
* tmp variable to be defined.
*/
#define SWAP(x, y) { tmp = (x); (x) = (y); (y) = tmp; }
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This macro fails to expand correctly in some case, such as the following example, which is meant to be an if statement with two branches:
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/*
* Swaps two values and requires
* tmp variable to be defined.
*/
#define SWAP(x, y) \
do { \
tmp = (x); \
(x) = (y); \
(y) = tmp; } \
while (0)
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The do-while loop will always be executed exactly once.
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