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For these reasons, it is important to ensure that operations on signed integers do no result in overflow. (See MSC15-C. Do not depend on undefined behavior.) Of particular importance are operations on signed integer values that originate from from a tainted source and are used as:
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The C Standard, 6.5.7 paragraph 4 [ISO/IEC 9899:2011], states
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In almost every case, an attempt to shift by a negative number of bits or by more bits than exist in the operand indicates a bug (logic error). These issues are covered by INT34-C. Do not shift a negative number of bits or more bits than exist in the operand.
Noncompliant Code Example
This noncompliant code example can result in an unrepresentable value.
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Compliant Solution
This compliant solution eliminates the possibility of overflow resulting from a left-shift operation:
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