python write text file line by line code example

Example 1: python read file line by line

with open("file.txt") as file_in:
    lines = []
    for line in file_in:
        lines.append(line)

Example 2: python writeline file

f = open("test.txt", "w")
f.writelines(["Hello", "World"])
f.close

Example 3: how to read a text file line by line in python

# Open the file with read only permit
f = open('my_text_file.txt')
# use readline() to read the first line 
line = f.readline()
# use the read line to read further.
# If the file is not empty keep reading one line
# at a time, till the file is empty
while line:
    # in python 2+
    # print line
    # in python 3 print is a builtin function, so
    print(line)
    # use realine() to read next line
    line = f.readline()
f.close()

Example 4: python writeline file

f = open("test.txt", "w")
f.write("Hello \nWorld")
f.close

Example 5: python output to text file

$ python my_program.py > output.txt