Difference between revisions of "C programming/Caveats"
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The statement of the left side of && evaluates to ''false'' the rigth side of the statement is never evaluated - and j is never incremented. | The statement of the left side of && evaluates to ''false'' the rigth side of the statement is never evaluated - and j is never incremented. | ||
| + | |||
| + | <br/>or<br/> | ||
| + | |||
| + | <source lang=c> | ||
| + | i=0; | ||
| + | j=8; | ||
| + | if (( i == 0 ) || (( j++ ) > 0 )) { | ||
| + | ...code... | ||
| + | } | ||
| + | </source> | ||
| + | The statement of the left side of || evaluates to ''true'' the rigth side of the statement is never evaluated - and j is never incremented. | ||
| + | |||
=Links= | =Links= | ||
*[http://www.eetimes.com/electronics-blogs/other/4394720/Sequence-points-?Ecosystem=embedded&cid=Newsletter+-+Whats+New+on+Embedded.com C Sequence points] | *[http://www.eetimes.com/electronics-blogs/other/4394720/Sequence-points-?Ecosystem=embedded&cid=Newsletter+-+Whats+New+on+Embedded.com C Sequence points] | ||
Latest revision as of 16:17, 10 February 2013
This article contains C programming syntaxes and equations that behave in a strange way.
Logical && and logical ||
When using the logical AND (&&) or the logical OR (||) the expression is evaluated from left to right. Consider the following code.
i=1;
j=8;
if (( i == 0 ) && (( j++ ) > 0 )) {
...code...
}
The statement of the left side of && evaluates to false the rigth side of the statement is never evaluated - and j is never incremented.
or
i=0;
j=8;
if (( i == 0 ) || (( j++ ) > 0 )) {
...code...
}
The statement of the left side of || evaluates to true the rigth side of the statement is never evaluated - and j is never incremented.