I have this simple python program. I ran it and it prints yes, when in fact I expect it to not print anything because 14 is not greater than 14.
I saw this related question, but it isn't very helpful.
#! /usr/bin/python
import sys
hours = "14"
if (hours > 14):
print "yes"
What am I doing wrong?
解决方案
Convert the string to an integer with int:
hours = int("14")
if (hours > 14):
print "yes"
In CPython2, when comparing two non-numerical objects of different types, the comparison is performed by comparing the names of the types. Since 'int' < 'string', any int is less than any string.
In [79]: "14" > 14
Out[79]: True
In [80]: 14 > 14
Out[80]: False
This is a classic Python pitfall. In Python3 this wart has been corrected -- comparing non-numerical objects of different type raises a TypeError by default.
CPython implementation detail: Objects of different types except
numbers are ordered by their type names; objects of the same types
that don’t support proper comparison are ordered by their address.