﻿ V3003. The use of 'if (A) {...} else if (A) {...}' pattern was detected. There is a probability of logical error presence.

# V3003. The use of 'if (A) {...} else if (A) {...}' pattern was detected. There is a probability of logical error presence.

The analyzer has detected a potential error in a construct consisting of conditional statements. Consider the following example:

``````if (a == 1)
Foo1();
else if (a == 2)
Foo2();
else if (a == 1)
Foo3();``````

In this code, the 'Foo3()' method will never get control. We are most likely dealing with a logical error here and the correct version of this code should look as follows:

``````if (a == 1)
Foo1();
else if (a == 2)
Foo2();
else if (a == 3)
Foo3();``````

In practice though, errors of this type can take more complicated forms, as shown below.

For example, the analyzer has found the following incorrect construct.

``````....
} else if (b.NodeType == ExpressionType.Or ||
b.NodeType == ExpressionType.OrEqual){
current.Condition = ConstraintType.Or;
} else if(...) {
....
} else if (b.NodeType == ExpressionType.OrEqual ||
b.NodeType == ExpressionType.Or){
current.Condition = ConstraintType.Or |
ConstraintType.Equal;
} else if(....``````

In this example, the uppermost if statement checks the following condition:

``````b.NodeType == ExpressionType.Or ||
b.NodeType == ExpressionType.OrEqual.``````

while the lowermost if statement checks a condition with the same logic but written in a reverse order, which is hardly noticeable for a human yet results in a runtime error.

``````b.NodeType == ExpressionType.OrEqual ||
b.NodeType == ExpressionType.Or``````
 According to Common Weakness Enumeration, potential errors found by using this diagnostic are classified as CWE-570.
 You can look at examples of errors detected by the V3003 diagnostic.

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