Writing before specific line python

Question

i have this piece of code:

asm = open(infile)
asmw = open(outfile, "w")
shutil.copyfile(infile, outfile)
for x in range(0, 8):
    xorreg.append("xor " +  reg[x] + ", " +  reg[x])
for line in asm:
    if any(s in line for s in xorreg):
    found += line.count(xorreg[x])
    print line

i want to write some text lines in the file right before "line" (the one printed) how can i do that?

Thanks

but that way the line that i wanna write would be after the one i looked for, no? — Lucca Zenobio
– Lucca Zenobio, Commented Dec 13, 2014 at 23:12

Reut Sharabani · Accepted Answer · 2014-12-13 23:24:09Z

4

This script appends to every lien containing the string Gandalf a new string The greatest wizard of all times was:

# show what's in the file
with open("some_file.txt", 'r') as f:
    print f.read()

new_content = []
with open("some_file.txt", "r") as asmr:
    for line in asmr.readlines():
        if "Gandalf" in line:
            # we have a match,we want something but we before that...
            new_content += "The greatest wizard of all times was:"
        new_content += line

# write the file with the new content
with open("some_file.txt", "w") as asmw:
    asmw.writelines(new_content)

# show what's in the file now
with open("some_file.txt", 'r') as f:
    print f.read()

answered Dec 13, 2014 at 23:24

Reut Sharabani

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2 Comments

Lucca Zenobio Over a year ago

thanks for that. the problem is that i dont wanna show the file, im showing only the lines that contains some element of my xorreg[] array. and these elements are the ones that i want to write before

Reut Sharabani Over a year ago

What do you mean by show? You don't have to show the file, this was just for anyone reading this to be clearer. You only need to re write the file, and when you encounter a row you want to add a line before, you need to add the new line and only than the original line.

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