python - f.readline() != '0' even if reading a line containing only 0 -

i not have trouble setting variables in program var = f.readline() function, having trouble if statement when comes reading out of text file. trying see if 0 in text file , every time use if f.readline() == '0': acts if not equal 0.

example of script below:

f = open("file.txt","r")  myvar = f.readline() f.close    if myvar == "0":     print "the variable 0"     raw_input("press enter continue") else:     print "the variable not 0"     raw_input("press enter continue") 

my code come out the variable not 0

why this? , how can use if statement readline function?

the readline method not remove trailing newlines lines. need manually:

myvar = f.readline().rstrip() 

otherwise, myvar equal "0\n", not equal "0".

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also, forgot close file calling close method:

f.close() # notice parenthesis 

of course, using with-statement better:

with open("file.txt") f:     myvar = f.readline().rstrip() 

with automatically close file when control leaves code block.