CODEWITHSUNDEEP
python
Warden Huang
Warden Huang

Reputation: 23

if statement is skipped even the statement is true

I just began on the TCP server and client programming on python. however one of the of the if statement does not work and it does not make any sense:

while (1):
    data = s.recv(1024)
    if data == 'finish':
         break
    print data
print 'Finish'

and sometimes the last lane will print 'finish' in stead of 'Finish' and it cant exit the loop. This should be never happened because the 'print data' statement is skipped if data='finish'. Could someone tell me why this is happening?

Upvotes: 1

Views: 96

Answers (3)

Weeble
Weeble

Reputation: 17960

Just because you sent the bytes in one call to send does not mean that you will receive them in one call to recv. They might arrive in smaller or larger groups. E.g. perhaps you send:

c.send('one')
c.send('two')
c.send('three')
c.send('finish')

But you receive

s.recv(1024) -> 'onetwothreefinish'

Or maybe you receive

s.receive(1024) -> 'one'
s.receive(1024) -> 'two'
s.receive(1024) -> 'three'
s.receive(1024) -> 'fin'
s.receive(1024) -> 'ish'

Upvotes: 3

danidee
danidee

Reputation: 9634

you can just compare with data.lower to ensure that all uppercase letters are changed to lowercase letters, also change the while loop and remove the redundant braces

while True:
    data = s.recv(1024)
    if not data:
         break
    print data
print 'Finish

Upvotes: 1

Jase Rieger
Jase Rieger

Reputation: 621

The comparison is case sensitive. Use data.lower() in the if statement

Upvotes: 0

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