Python初识逻辑与if语句及用法大全

逻辑判断与逻辑语句

• 对于─件事情正确与否（真假的判断) √ x
• 根据判断的结果做不同的事情，就是我们的逻辑业务
• 对于条件满足的判断语句，就是条件语句
• 一个逻辑语句是由条件语句和业务语句组合而成

 

if语句功能

判断一个命题的真实性，如果命题为真( true )则执行if的逻辑语句

 if语句用法

用法:

if bool_result: # 语法块
	do # 业务代码块注意缩进

参数︰

•  bool_result: 判断结果的真假，布尔类型
• do: 如果bool_result为true时执行任意python代码

返回值: if属于关键字，没有返回值

>>> insane_status = 'hunger
>>> if insane_status == 'hunger':
		print( 'xiaomu invites insane to dinner' )
		
xiaomu invites insane to dinner

实战

# coding:utf-8

info = 'my name is insane'

info_list = info.split()
print(info_list)

if info_list[0] == 'insane':
    print(1)
    info_list[0] = 'loafer'

if info_list[1] == 'insane':
    print(2)
    info_list[1] = 'loafer'

if info_list[2] == 'insane':
    print(3)
    info_list[2] = 'loafer'

if info_list[-1] == 'insane':
    print(4)
    info_list[-1] = 'loafer'

print(info_list)
info = ' '.join(info_list)
print(info)

info = 'my name is insane, i am a pythoner, i love python'
info_list = info.split()

if info_list[0] in ['python', 'i']:
    info_list[0] = '*'

if info_list[1] == 'python' or info_list[1] == 'i':
    info_list[1] = '*'

if info_list[2] == 'python' or info_list[2] == 'i':
    info_list[2] = '*'

if info_list[3] == 'python' or info_list[3] == 'i':
    info_list[3] = '*'

if info_list[4] == 'python' or info_list[4] == 'i':
    info_list[4] = '*'

if info_list[5] == 'python' or info_list[5] == 'i':
    info_list[5] = '*'

if info_list[6] == 'python' or info_list[6] == 'i':
    info_list[6] = '*'

if info_list[7] == 'python' or info_list[7] == 'i':
    info_list[7] = '*'

if info_list[8] == 'python' or info_list[8] == 'i':
    info_list[8] = '*'

if info_list[9] == 'python' or info_list[9] == 'i':
    info_list[9] = '*'

if info_list[-1] in ['python', 'i']:
    info_list[-1] = '*'

print(info_list)
info = ' '.join(info_list)
print(info)

info = 'my name is insane'
print(len(info))

if len(info) > 10 and len(info) != 15:
    print(info.replace('insane', 'loafer'))

if len(info) > 10 and len(info) != 17:
    print(info.replace('name', 'iop'))

print('finish')

['my', 'name', 'is', 'insane']
4
['my', 'name', 'is', 'loafer']
my name is loafer
['my', 'name', 'is', 'insane,', '*', 'am', 'a', 'pythoner,', '*', 'love', '*']
my name is insane, * am a pythoner, * love *
17
my name is loafer
finish

process finished with exit code 0

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