if 语句

if exp: # 条件真 # 你要执行的代码

In [ ]:
if 1 == 1:
    print("1==1")
    print(1==1) # 1 and 0, or

In [ ]:
if (1==1):
    print("1 == 1") # print "1 == 1"
if exp: # 条件真 # 你要执行的代码 else: # 条件假 # 你要执行的代码

In [ ]:
if 1 == 0:
    print("1 == 0")
else:
    print('1 != 0')

In [ ]:
exp = 2

if exp == 0:
    print("exp == 0")

if exp == 1:
    print("exp == 1")
    
if exp == 2:
    print("exp == 2")
if exp: # 条件真 # 你要执行的代码 elif exp: # 条件真 # 你要执行的代码

In [ ]:
exp = 1

if exp == 0:
    print("exp == 0")

elif exp == 1:
    print("exp == 1")
    
elif exp == 2:
    print("exp == 2")
if exp: # 条件真 # 你要执行的代码 elif exp: # 条件真 # 你要执行的代码 else: # 条件假 # 你要执行的代码

In [ ]:
exp = -1

if exp == 0:
    print("exp == 0")

elif exp == 1:
    print("exp == 1")
    
elif exp == 2:
    print("exp == 2")
else:
    print('exp == %i' % exp)

In [ ]:
if exp == 0:
    print("exp == 0")
    if exp == 1:
        print("exp == 1")
    else:
        print('exp == %i' % exp)
elif exp ==1 :
    print("exp == 1")

条件表达式


In [ ]:
exp = 0
if exp > 4:
    exp = 3
else:
    exp = 1
print(exp)

In [ ]:
exp = 6
exp = 3 if exp > 4 else 1
print(exp)

In [ ]:
# --------------------------------------------------------------------------------  
# Copyright (c) 2013 - 2014 Mack Stone. All rights reserved.  
#   
# Permission is hereby granted, free of charge, to any person obtaining a copy  
# of this software and associated documentation files (the "Software"), to deal  
# in the Software without restriction, including without limitation the rights  
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell  
# copies of the Software, and to permit persons to whom the Software is  
# furnished to do so, subject to the following conditions:  
#   
# The above copyright notice and this permission notice shall be included in  
# all copies or substantial portions of the Software.  
#   
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR  
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,  
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE  
# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER  
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,  
# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN  
# THE SOFTWARE.  
# --------------------------------------------------------------------------------