Python编程---if条件语句

                                   if条件语句

1、if...

#! /usr/bin/python
#coding:utf-8

x=10
if x>0:
       print "x=%d"%(x)

NOTE：语句块需要有indentation block，且indentation block必须为4个space。

2、if...else...

#! /usr/bin/python
#coding:utf-8

x=10
if x>10:
      print "x=%d"%(x)
      print "x={}".format(x)
      print "if ... statement end"
else:
      print "x=%d"%(x)
      print "x={}".format(x)
      print "if ... statement3 end"

print "out of if ... structure!!!"

3、if...elif...else

#! /usr/bin/python
#coding:utf-8

x=10
if x>10:
      print "x=%d"%(x)
      print "x={}".format(x)
      print "if ... statement end"
elif x>20:
      print "x=%d"%(x)
      print "x={}".format(x)
      print "if ... statement1 end"
elif x==10:
      print "x=%d"%(x)
      print "x={}".format(x)
      print "if ... statement3 end"

print "out of if ... structure!!!"

4、if语句块结构

#! /usr/bin/python
#coding:utf-8

x=10
if x>0:
       print "x=%d"%(x)
       print "x={}".format(x)
       print "if ... statement end"
print "out of if ... structure!!!"

分析：紧跟if后面的语句若都是以if为基准的四个空格开头，那么都是该if的语句块。

5、if True...else...

#! /usr/bin/python
#coding:utf-8

x=10
if True:
      print "x=%d"%(x)
      print "x={}".format(x)
      print "if ... statement end"
else:
      print "x=%d"%(x)
      print "x={}".format(x)
      print "if ... statement3 end"

print "out of if ... structure!!!"