Replace a word in a file

Question

I am new to Python programming...

I have a .txt file....... It looks like..

0,Salary,14000

0,Bonus,5000

0,gift,6000

I want to to replace

Answer 1

o=open("output.txt","w")
for line in open("file"):
    s=line.split(",")
    s[0]="1"
    o.write(','.join(s))
o.close()

Or you can use fileinput with in place edit

import fileinput
for line in fileinput.FileInput("file",inplace=1):
    s=line.split(",")
    s[0]="1"
    print ','.join(s)