Home >Backend Development >C++ >How Can I Reliably Detect C 'for' and 'while' Loops Ending with a Semicolon?

How Can I Reliably Detect C 'for' and 'while' Loops Ending with a Semicolon?

Linda Hamilton
Linda HamiltonOriginal
2024-12-15 18:09:10229browse

How Can I Reliably Detect C

Detecting C "for" and "while" Loops with Semi-Colon Termination

Matching C for or while loops that end with a semi-colon using a regular expression can be challenging. A common approach involves creating a named group to match balanced substrings, ensuring that the entire loop body is contained within parentheses.

However, this method falters when the loop body includes a function call, breaking the balance. A simplified approach using a non-regex function can overcome this issue.

Custom Function for Loop Matching

The following custom function takes an input string and searches for a for or while loop followed by a semi-colon:

def find_loop_and_semicolon(string):
    pos = string.find('(') + 1
    open_br = 0
    while open_br >= 0:
        char = string[pos]
        if char == '(':
            open_br += 1
        elif char == ')':
            open_br -= 1
        pos += 1
    return pos if open_br == 0 and string[pos] == ';' else -1

The function:

  1. Sets the position counter pos to the position just before the opening bracket of the loop.
  2. Initializes an open bracket counter open_br to 0.
  3. Iterates through the string, incrementing open_br for opening brackets and decrementing it for closing brackets.
  4. When open_br returns to 0, the position of the closing bracket is reached.
  5. Checks if the character at the next position is a semi-colon to confirm loop termination.
  6. Returns pos if both conditions are met or -1 otherwise.

Usage

string = "for (int i = 0; i < 10; doSomethingTo(i));"
result = find_loop_and_semicolon(string)
if result != -1:
    print("Loop found and terminated with a semi-colon.")
else:
    print("No matching loop found.")

Advantages

  • Simplicity: The function is easy to understand and implement.
  • Flexibility: It handles loops with complex bodies, including function calls.
  • No Regex Overhead: Avoids the potential overhead and complexity of regular expressions.

The above is the detailed content of How Can I Reliably Detect C 'for' and 'while' Loops Ending with a Semicolon?. For more information, please follow other related articles on the PHP Chinese website!

Statement:
The content of this article is voluntarily contributed by netizens, and the copyright belongs to the original author. This site does not assume corresponding legal responsibility. If you find any content suspected of plagiarism or infringement, please contact admin@php.cn