Basic¶
BitwiseOperatorInConditional¶
Since: 0.6
Name: bitwise operator in conditional
Checks for bitwise operations in conditionals. Although being written on purpose in some rare cases, bitwise operations are considered to be too “smart”. Smart code is not easy to understand.
This rule is defined by the following class: oclint-rules/rules/basic/BitwiseOperatorInConditionalRule.cpp
Example:
void example(int a, int b)
{
if (a | b)
{
}
if (a & b)
{
}
}
BrokenNullCheck¶
Since: 0.7
Name: broken null check
The broken null check itself will crash the program.
This rule is defined by the following class: oclint-rules/rules/basic/BrokenNullCheckRule.cpp
Example:
void m(A *a, B *b)
{
if (a != NULL || a->bar(b))
{
}
if (a == NULL && a->bar(b))
{
}
}
BrokenNilCheck¶
Since: 0.7
Name: broken nil check
The broken nil check in Objective-C in some cases returns just the opposite result.
This rule is defined by the following class: oclint-rules/rules/basic/BrokenNullCheckRule.cpp
Example:
+ (void)compare:(A *)obj1 withOther:(A *)obj2
{
if (obj1 || [obj1 isEqualTo:obj2])
{
}
if (!obj1 && ![obj1 isEqualTo:obj2])
{
}
}
BrokenOddnessCheck¶
Since: 0.6
Name: broken oddness check
Checking oddness by x % 2 == 1
won’t work for negative numbers. Use x & 1 == 1
, or x % 2 != 0
instead.
This rule is defined by the following class: oclint-rules/rules/basic/BrokenOddnessCheckRule.cpp
Example:
void example()
{
if (x % 2 == 1) // violation
{
}
if (foo() % 2 == 1) // violation
{
}
}
CollapsibleIfStatements¶
Since: 0.6
Name: collapsible if statements
This rule detects instances where the conditions of two consecutive if statements can be combined into one in order to increase code cleanness and readability.
This rule is defined by the following class: oclint-rules/rules/basic/CollapsibleIfStatementsRule.cpp
Example:
void example(bool x, bool y)
{
if (x) // these two if statements can be
{
if (y) // combined to if (x && y)
{
foo();
}
}
}
ConstantConditionalOperator¶
Since: 0.6
Name: constant conditional operator
conditional operator
whose conditionals are always true or always false are confusing.
This rule is defined by the following class: oclint-rules/rules/basic/ConstantConditionalOperatorRule.cpp
Example:
void example()
{
int a = 1 == 1 ? 1 : 0; // 1 == 1 is actually always true
}
ConstantIfExpression¶
Since: 0.2
Name: constant if expression
if
statements whose conditionals are always true or always false are confusing.
This rule is defined by the following class: oclint-rules/rules/basic/ConstantIfExpressionRule.cpp
Example:
void example()
{
if (true) // always true
{
foo();
}
if (1 == 0) // always false
{
bar();
}
}
DeadCode¶
Since: 0.4
Name: dead code
Code after return
, break
, continue
, and throw
statements is unreachable and will never be executed.
This rule is defined by the following class: oclint-rules/rules/basic/DeadCodeRule.cpp
Example:
void example(id collection)
{
for (id it in collection)
{
continue;
int i1; // dead code
}
return;
int i2; // dead code
}
DoubleNegative¶
Since: 0.6
Name: double negative
There is no point in using a double negative, it is always positive.
This rule is defined by the following class: oclint-rules/rules/basic/DoubleNegativeRule.cpp
Example:
void example()
{
int b1 = !!1;
int b2 = ~~1;
}
ForLoopShouldBeWhileLoop¶
Since: 0.6
Name: for loop should be while loop
Under certain circumstances, some for
loops can be simplified to while loops to make code more concise.
This rule is defined by the following class: oclint-rules/rules/basic/ForLoopShouldBeWhileLoopRule.cpp
Example:
void example(int a)
{
for (; a < 100;)
{
foo(a);
}
}
GotoStatement¶
Since: 0.6
Name: goto statement
“Go To Statement Considered Harmful”
This rule is defined by the following class: oclint-rules/rules/basic/GotoStatementRule.cpp
Example:
void example()
{
A:
a();
goto A; // Considered Harmful
}
References:
Edsger Dijkstra (March 1968). “Go To Statement Considered Harmful”. Communications of the ACM (PDF) 11 (3): 147–148. doi:10.1145/362929.362947.
JumbledIncrementer¶
Since: 0.7
Name: jumbled incrementer
Jumbled incrementers are usually typos. If it’s done on purpose, it’s very confusing for code readers.
This rule is defined by the following class: oclint-rules/rules/basic/JumbledIncrementerRule.cpp
Example:
void aMethod(int a) {
for (int i = 0; i < a; i++) {
for (int j = 0; j < a; i++) { // references both 'i' and 'j'
}
}
}
MisplacedNullCheck¶
Since: 0.7
Name: misplaced null check
The null check is misplaced. In C and C++, sending a message to a null pointer could crash the program. When null is misplaced, either the check is useless or it’s incorrect.
This rule is defined by the following class: oclint-rules/rules/basic/MisplacedNullCheckRule.cpp
Example:
void m(A *a, B *b)
{
if (a->bar(b) && a != NULL) // violation
{
}
if (a->bar(b) || !a) // violation
{
}
}
MisplacedNilCheck¶
Since: 0.7
Name: misplaced nil check
The nil check is misplaced. In Objective-C, sending a message to a nil pointer simply does nothing. But code readers may be confused about the misplaced nil check.
This rule is defined by the following class: oclint-rules/rules/basic/MisplacedNullCheckRule.cpp
Example:
+ (void)compare:(A *)obj1 withOther:(A *)obj2
{
if ([obj1 isEqualTo:obj2] && obj1)
{
}
if (![obj1 isEqualTo:obj2] || obj1 == nil)
{
}
}
MultipleUnaryOperator¶
Since: 0.6
Name: multiple unary operator
Multiple unary operator can always be confusing and should be simplified.
This rule is defined by the following class: oclint-rules/rules/basic/MultipleUnaryOperatorRule.cpp
Example:
void example()
{
int b = -(+(!(~1)));
}
ReturnFromFinallyBlock¶
Since: 0.6
Name: return from finally block
Returning from a finally
block is not recommended.
This rule is defined by the following class: oclint-rules/rules/basic/ReturnFromFinallyBlockRule.cpp
Example:
void example()
{
@try
{
foo();
}
@catch(id ex)
{
bar();
}
@finally
{
return; // this can discard exceptions.
}
}
ThrowExceptionFromFinallyBlock¶
Since: 0.6
Name: throw exception from finally block
Throwing exceptions within a finally
block may mask other exceptions or code defects.
This rule is defined by the following class: oclint-rules/rules/basic/ThrowExceptionFromFinallyBlockRule.cpp
Example:
void example()
{
@try {;}
@catch(id ex) {;}
@finally {
id ex1;
@throw ex1; // this throws an exception
NSException *ex2 = [NSException new];
[ex2 raise]; // this throws an exception, too
}
}