for循环中的sys.stdin无法获取用户输入

Question

I have this code ( test.py ) below:

import sys    
for str in sys.stdin.readline():
    print ('Got here')
    print(str)

For some reason when I run the program python test.py and then I type in abc into my terminal I get this output:

>>abc
THIS IS THE OUTPUT:
Got here
a
Got here
b
Got here
c
Got here

It prints out Got here five times and it also prints out each character a , b , c individually rather than one string like abc . I am doing sys.stdin.readline() to get the entire line but that doesn't seem to work either. Does anyone know what I am doing wrong?

I am new to python and couldn't find this anywhere else on stackoverflow so sorry if this is a obvious question.

Answer 1

readline() reads a single line. Then you iterate over it. Iterating a string gives you the characters, so you are running your loop once for each character in the first line of input.

Use .readlines(), or better, just iterate over the file:

for line in sys.stdin:

But the best way to get interactive input from stdin is to use input() (or raw_input() in Python 2).

Answer 2

You are looping through each character in the string that you got inputted.

import sys    
s = sys.stdin.readline()
print ('Got here')
print(s)

# Now I can use string `s` for whatever I want
print(s + "!")

In your original code you got a string from stdin and then you looped through ever character in that input string and printed it out (along with "Got here").

EDIT:

import sys
while True:
    s = sys.stdin.readline()

    # Now I can do whatever I want with string `s`
    print(s + "!")