printing next several lines after if statements in python-CodePudding

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" )

CodePudding user response：

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])

CodePudding user response：

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

CodePudding user response：

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! :)

CodePudding user response：

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])