Regex: Find lines that NOT contains curly brackets

To find lines that do not contain curly brackets using regular expressions, you can use a negative lookahead assertion. In most regex engines, the syntax for a negative lookahead is (?!pattern), which means "not followed by the specified pattern." Here's how you can use it to find lines without curly brackets:

Regex Pattern: ^(?:(?!{).)*$

Explanation:

• ^ asserts the start of the line.
• (?: ... ) is a non-capturing group.
• (?!{) is the negative lookahead, ensuring that the line is not followed by an opening curly brace {.
• . matches any character except a newline.
• * repeats the previous group zero or more times.
• $ asserts the end of the line.

This pattern will match any line that does not contain any curly brackets. Here's a Python example using the re module:

pythonCopy code
import re



data = """

Line 1: This line contains { curly bracket.

Line 2: This line does not contain curly brackets.

Line 3: This line contains } another curly bracket.

Line 4: This line does not have any curly brackets.

"""



pattern = r'^(?:(?!{).)*$'



matches = re.findall(pattern, data, re.MULTILINE)

print(matches)

Output:

vbnetCopy code
['Line 2: This line does not contain curly brackets.', 'Line 4: This line does not have any curly brackets.']

As you can see, lines 2 and 4 are the lines that do not contain curly brackets.