Sizeof with side effects¶

ID: cpp/sizeof-side-effectKind: problemSecurity severity: Severity: recommendationPrecision: highTags:   - reliability   - correctness   - external/jsfQuery suites:   - cpp-security-and-quality.qls

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This rule findssizeof expressions that have a parameter with side-effects.sizeof only uses the type of the parameter, so the parameter will not be evaluated. In the C99 standard, usingsizeof on expressions with dynamic arrays may or may not evaluate the side-effect, so it is better to avoid it completely.

intf(void){inti=0;chararr[20];intsize=sizeof(arr[i++]);//wrong: sizeof expression has side effectcout<<i;//would output 0 instead of 1}