printing next several lines after if statements in python

Question

I am new at python, im trying to write a code to print several lines after an if statement.

for example, I have a file "test.txt" with this style:

Hello how are you? fine thanks how old are you? 24 good how old are you? i am 26 ok bye. Hello how are you? fine how old are you? 13 good how old are you? i am 34 ok bye. Hello how are you? good how old are you? 17 good how old are you? i am 19 ok bye. Hello how are you? perfect how old are you? 26 good how old are you? i am 21 ok bye.

so I want to print one line after each "how old are you" my code is like this:

fhandle=open('test.txt') for line in fhandle: if line.startswith('how old are you?') print(line) /*** THIS IS THE PROBLEM

I want to print next line after how old are you ( maybe print two lines after "how old are you" )

Mohammad Khoshbin · Accepted Answer · 2021-12-05 14:32:16Z

You can use readlines() function that returnes lines of a file as a list and use enumerate() function to loop through list elements:

lines = open('test.txt').readlines() for i,line in enumerate(lines): if line.startswith('how old are you?'): print(lines[i+1], line[i+2])

Dornteufel · Accepted Answer · 2021-12-05 13:04:36Z

You could convert the file to a list and use a variable which increases by 1 for each line:

fhandle = list(open('test.txt')) i = 1 for line in fhandle: if line.startswith('how old are you?') print(fhandle[i]) i += 1

Riz · Accepted Answer · 2021-12-05 13:15:11Z

Assuming there are always two more lines after each "how old are you", you could just skip to the next iteration by using next(fhandle) like this:

fhandle = open('test.txt') for line in fhandle: if line.startswith('how old are you?'): print(line) print(next(fhandle)) print(next(fhandle))

Remember that the for loop just uses fhandle as an iterator! :)

Moein Kameli · Accepted Answer · 2021-12-05 13:16:46Z

So as you want to print next line (or two lines) I suggest to use list index. to do that use readlines() to convert the file to a list:

fhandle = open('test.txt').readlines()

After you did this you can use len to calculate list length and index it in a for loop and print next two lines.

for line_index in range(len(fhandle)): if fhandle[line_index].startswith('how old are you?'): print(fhandle[line_index + 1], fhandle[line_index + 2])

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