CODEWITHSUNDEEP
pythonregexreplace
SoBiT
SoBiT

Reputation: 408

Find and replace in multiple files and add incrementing number

I'm trying to replace a regex pattern in many .cpp files on my computer. I need to add an incrementing number at the end of each substitution, so I chose python to do this.

This is what I got already, but it doesn't work yet:

import os
import re
i = 0
for file in os.listdir("C:\SeparatorTest"):
    if file.endswith(".cpp"):
        for line in open(file):
            line = re.sub(r'([^\s]*)\.Separator\((.*)\)\;', r'Separator \1\_' + i += 1 + '(\1,\2);')

Have I missed something?

Upvotes: 0

Views: 1044

Answers (1)

PhilDenfer
PhilDenfer

Reputation: 270

Haven't tested because I didn't think of what you are trying to replace, but you shouldn't increment like that in the middle of your re.sub call, you need to replace your last line of code with this :

line = re.sub(r'([^\s]*)\.Separator\((.*)\)\;', r'Separator \1\_' + i + '(\1,\2);')
i += 1

In C++ you'd just put i++ or ++i and the expression would be evaluated to i before or after incrementation, but here I wouldn't try fancy things, python needs to be readable and the next programmer reading your code might not guess what you did. and there is no ++ operator in python.

Edit : And you are just reading your file, the open(file) has default "r", which means reading, and you aren't writing anything. you need open(file, "w") for that. and not just store the re.sub() return value in a variable, but write it to the file.

Edit2 : Here is what I'm working on, it's not done yet, I'll edit as I find how to get it to work :

import os, re
i = 0
def replacement(i):
    i += 1
    return r'Separator \1\_' + str(i) + '(\1,\2);'

for file in os.listdir("."):
    if file.endswith(".cpp"):
        for line in open(file):
            re.sub(r'([^\s]*)\.Separator\((.*)\)\;', replacement(i), line)

The idea is that the replacement text can be the result of a function that should only be called when a non overlapping pattern matches, according to The python documentation

Edit3 : I think I'll stop there, unless I get a response from you because I have some regex and other problems I don't have time to address. Also I'm unsure on best practice for text replacement, you should look for that, there should be help available. Glue the whole thing together (Incrementation, correcting your re.sub() call, open in writing mode, replace the text that matches) and you should achieve what you were trying to do.

Upvotes: 1

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