Can a Regular Expression Reliably Identify Properly Semi-Colon Terminated C For and While Loops?

Regular Expressions for Semi-Colon Terminated C For & While Loops

Challenge: Crafting a regular expression that discerns between:

• Properly terminated C for or while loops with semi-colons (;)
• Loops that lack semi-colon termination

Initial Attempt:

The provided initial regular expression effectively detects balanced parentheses within for/while statements. However, it struggles when the loop expression contains function calls.

^\s*(for|while)\s*
\(  # match the initial opening parenthesis
    (?P<balanced>
        [^()]
        |
        \( (?P=balanced)* \)
    )*  # Look for a sequence of balanced substrings
\)  # Finally, the outer closing parenthesis.
\s*;\s*

Revised Approach:

The suggested resolution deviates from a regex-based approach. Instead, it utilizes a simplistic routine:

1. Initialize pos to the character before the opening parenthesis of the for/while statement.
2. Establish an openBr counter with an initial value of 0.
3. Iterate through the string, incrementing pos and incrementing/decrementing openBr based on encountered parentheses.
4. Terminate iteration when openBr returns to 0.
5. Verify if a semicolon exists immediately after the closing parenthesis found in step 4.

Advantages:

• Simplicity and clarity
• No reliance on complex regular expressions
• Ability to handle loops with expressions containing function calls

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