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Providing an expression that appears to produce side effects may be misleading to programmers who are not aware that these expressions are not evaluated. As a result, programmers may make invalid assumptions about program state, leading to errors and possible software vulnerabilities.
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Non-Compliant Code Example
In this non-compliant code example, the expression a++ is not evaluated and the side effects in the expression are not executed.
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int a = 14;
int b = sizeof(a++);
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Consequently, the value of a after b has been initialized is 14.
Implementation-Specific Details
This example compiles cleanly under Microsoft Visual Studio 2005 Version 8.0, with the /W4 option.
Compliant Solution
In this compliant solution, the variable a is incremented.
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int a = 14;
int b = sizeof(a);
a++;
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Risk Assessment
If expressions that appear to produce side effects are supplied to the sizeof operator, the returned result may be different than expected. Depending on how this result is used, this could lead to unintended program behavior.
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