Replacing a string in a text file

[afshin]

Hello Python Experts

I have a text file containing a code (written for a software)

I need to write a code in Python, to first, read the text file, search for a string, change that string with something else and save the file.

Let's say that the file name is test.txt which is in D:\ry directory, and I need to change E=100 to E=200 in this file.

I should mention that I am a beginner in python.

Thansk

[bvdet]

It could be as simple as this:

>>> s = open("test12.txt").read()
>>> f = open("test13.txt", 'w')
>>> f.write(s.replace("E=100", "E=200"))
>>> f.close()
>>> 

[afshin]

Thanks. From you code, I wrote it like this:

s = open("D:\test.txt").read()
f = open("D:\test1.txt", 'w')
f.write(s.replace("E=100", "E=200"))
f.close()

But it gives me the following error:

Traceback (most recent call last):
File "D:\test2.py", line 7, in <module>
s = open("D:\test.txt").read()
IOError: [Errno 22] invalid mode ('r') or filename: 'D:\test.txt'

[bvdet]

If you use a backslash character in the file name, it's a good idea to always escape it as in "D:\\test.txt". Otherwise you could use the forward slash character "/". FYI - "\t" is interpreted as a tab character. "\\t" is interpreted as a backslash and t.

[afshin]

Thank you very much. As I am learning it, I will back to you with new questions soon ;)