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This code always results in g being assigned the value 2.

Exceptions

EXP10-C-EX1: The && and || operators guarantee left-to-right evaluation; there is a sequence point after the evaluation of the first operand.

EXP10-C-EX2: The first operand of a condition expression is evaluated; there is a sequence point after its evaluation. The second operand is evaluated only if the first compares unequal to 0; the third operand is evaluated only if the first compares equal to 0.

EXP10-C-EX3: There is a sequence point before function calls, meaning that the function designator, the actual arguments, and subexpressions within the actual arguments are evaluated before the function is invoked.

EXP10-C-EX4: The left operand of a comma operator is evaluated before the right operand is evaluated. There is a sequence point in between.

Note that whereas commas serve to delimit multiple arguments in a function call, these commas are not considered comma operators. Multiple arguments of a function call may be evaluated in any order, with no sequence points between each other.

Risk Assessment

Recommendation	Severity	Likelihood	Remediation Cost	Priority	Level
EXP10-C	Medium	Probable	Medium	P8	L2

Automated Detection

Tool

Version

Checker

Description

Astrée

Include Page

	Astrée_V
	Astrée_V

evaluation-order
multiple-volatile-accesses

Partially checked

Axivion Bauhaus Suite

Include Page

	Axivion Bauhaus Suite_V
	Axivion Bauhaus Suite_V

CertC-EXP10

Fully implemented

CodeSonar

Include Page

	CodeSonar_V
	CodeSonar_V

LANG.STRUCT.SE.IOE

Indeterminate Order of Evaluation

Compass/ROSE

Could detect violations of this recommendation by searching for the following pattern:

- Any expression that calls two functions between the same sequence points
- Those two functions both modify the value of a static variable
- That static variable's value is referenced by code following the expression

Coverity

Include Page

	Coverity_V
	Coverity_V

EVALUATION_ORDER

Can detect the specific instance where a statement contains multiple side effects on the same value with an undefined evaluation order because the statement may behave differently with different compiler flags or different compilers or platforms

Helix QAC

Include Page

	Helix QAC_V
	Helix QAC_V

C0400, C0401, C0402, C0403, C0404, C0405, C3226, C3326

LDRA tool suite

Include Page

	LDRA_V
	LDRA_V

35 D

, 72 D

74 D

, 1 Q

, 134 S

Fully implemented

PRQA QA-C Include PagePRQA QA-C_vPRQA QA-C_v3226,3326,0400, 0401, 0402,0403

Parasoft C/C++test

Include Page

	Parasoft_V
	Parasoft_V

CERT_C-EXP10-a
CERT_C-EXP10-b
CERT_C-EXP10-c
CERT_C-EXP10-d

The value of an expression shall be the same under any order of evaluation that the standard permits
Don't write code that depends on the order of evaluation of function arguments
Don't write code that depends on the order of evaluation of function designator and function arguments
Don't write code that depends on the order of evaluation of expression that involves a function call

PC-lint Plus

Include Page

	PC-lint Plus_V
	PC-lint Plus_V

564, 931

Partially supported

Polyspace Bug Finder

Include Page

	Polyspace Bug Finder_V
	Polyspace Bug Finder_V

CERT C: Rec. EXP10-C

Checks for situations where expression value depends on order of evaluation or side effects (rec. fully covered)

PVS-Studio

Include Page

	PVS-Studio_V
	PVS-Studio_V

V521, V681

RuleChecker

Include Page

	RuleChecker_V
	RuleChecker_V

evaluation-order
multiple-volatile-accesses

Partially checked

Partially implemented

A programmer could also violate the recommendation using dynamic memory passed to both functions, but that would be extremely difficult to detect using static analysis.

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Search for vulnerabilities resulting from the violation of this rule on the CERT website.