开始
用数据做判断:布尔值
例:布尔运算
print(3<5)
print(3>5)
print('长安'=='长安')
print('长安'!='金陵')
True
False
True
True
例:while判断
while False:
print('while False')
while 3>5:
print('while False')
#什么都不显示
例:if循环
if False:
print('if False')
if True:
print('if True')
![image.png](/uploads/projects/jitangshaobing@mfgp3o/171f5759e2fe77e9767cb52db3c914f1.png)
两个数值做比较
![image.png](/uploads/projects/jitangshaobing@mfgp3o/6de6287fcb2d8418e3a82352ecb32045.png)
例:= 、== 区分
password = input('请输入密码:')
if password == 'abc':
print('密码正确!')
else:
print('密码错误!')
直接用数值做运算
例:数值“1”
if 1:
print('熊猫')
#结果
熊猫
![image.png](/uploads/projects/jitangshaobing@mfgp3o/320758793774aa599a944e734601d9a9.png)
例:bool()
函数
print('以下数据判断结果都是【假】:')
print(bool(False))
print(bool(0))
print(bool(''))
print(bool(None))
print('以下数据判断结果都是【真】:')
print(bool(True))
print(bool(1))
print(bool('abc'))
布尔值之间的运算
例:and和or运算
a = 1
b = -1
print('以下是and运算')
if a==1 and b==1: # 【b实际上是-1】
print('True')
else:
print('False')
print('以下是or运算')
if a==1 or b==1: # 【b实际上是-1】
print('True')
else:
print('False')
![image.png](/uploads/projects/jitangshaobing@mfgp3o/dbda8f79ab3de3b9985ec6b1eb676624.png)
![image.png](/uploads/projects/jitangshaobing@mfgp3o/7fc675f6dc59ef10be62540070656f13.png)
![image.png](/uploads/projects/jitangshaobing@mfgp3o/5883455a1756126b91079f3b216afc5b.png)
例:in运算
list = [1,2,3,4,5]
a = 1
# 做一次布尔运算,判断“a是否在列表list之中”
print(bool(a in list))
print(bool(a not in list))
#结果
True
False
![image.png](/uploads/projects/jitangshaobing@mfgp3o/47d8781d3250525baae0956d6d533dda.png)
![image.png](/uploads/projects/jitangshaobing@mfgp3o/2f6ff0fd6d480b5921b14e396135fc9d.png)
![image.png](/uploads/projects/jitangshaobing@mfgp3o/a5232fcfa29eb72d4148efddc9f5365b.png)