CODEWITHSUNDEEP
pythonpython-2.7
Vibhav Mishra
Vibhav Mishra

Reputation: 1

Python if statement not executing

#   TEST
import sys  
a=sys.stdin.readline()    # here the user inputs the string "HELLO"  
print a
if a == "HELLO":  
    sys.stdout.write("GOOD_BYE")  
print "AAAAAAAAAAA"  
raw_input('\npress any key to continue')

Hi there. I am new to Python.
I am using Python 2.7.11.
I do not understand why control is not entering the if statement.
The output for the given code comes out as

HELLO  
HELLO   
AAAAAAAAAAA
press any key to continue

NOTE: The first "HELLO" above is user input
I've tried sys.stdout.flush() for the sys.stdout.write() statement. But it doesn't seem to help.
If I write the same code with a=raw_input() instead of the second line, it works perfectly fine.
Can anyone explain the reason for this.

Upvotes: 0

Views: 106

Answers (4)

Pankaj Kumar
Pankaj Kumar

Reputation: 61

You are pressing 'ENTER' after input string to send input. So your input is 'HELLO\n' while your if statement 'if' condition is 'a == "HELLO"'.

Use strip() method. The method strip() returns a copy of the string in which all chars have been stripped from the beginning and the end of the string (default whitespace characters).

So new working code :

import sys  
a=sys.stdin.readline().rstrip('\n')
a=a.strip() # This will remove \n from input
print (a)
if a == "HELLO":  
    sys.stdout.write("GOOD_BYE")  
print ("AAAAAAAAAAA")
raw_input('\npress any key to continue')

Upvotes: 0

Abhijit Saxena
Abhijit Saxena

Reputation: 28

Try using 'in' instead of '==' in your if condition, sometimes the lines might have some hidden characters.

if "HELLO" in a:

Upvotes: 0

Sangam Belose
Sangam Belose

Reputation: 4506

readline() function read newline character from standard input console. Please use rstrip("\n") to remove the same.

import sys  
a=sys.stdin.readline().rstrip('\n')
print (a)
if a == "HELLO":  
    sys.stdout.write("GOOD_BYE")  
print ("AAAAAAAAAAA")
raw_input('\npress any key to continue')

Upvotes: 0

Vj-
Vj-

Reputation: 722

readline comes with a newline character at the end. So what you are actually doing is comparing 

HELLO\n == HELLO

which is actually false.

Do a.rstrip() to remove newline.

Upvotes: 2

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