分⽀结构
⽤户身份验证
"""
username = input('请输⼊⽤户名: ')
password = input('请输⼊⼝令: ')
# ⽤户名是admin且密码是123456则身份验证成功否则身份验证失败
if username == 'admin' and password == '123456':
print('身份验证成功!')
else:
print('身份验证失败!')
分段函数求值
3x - 5 (x > 1)
f(x) = x + 2 (-1 <= x <= 1)
5x + 3 (x < -1)
"""
x = float(input('x = '))
if x > 1:
y = 3 * x - 5
elif x >= -1:
y = x + 2
else:
y = 5 * x + 3
print('f(%.2f) = %.2f' % (x, y))
练习3：输⼊三条边⻓，如果能构成三⻆形就计算周⻓和⾯积。
a = float(input('a = '))
b = float(input('b = '))
c = float(input('c = '))
if a + b > c and a + c > b and b + c > a:
print('周⻓: %f' % (a + b + c))
p = (a + b + c) / 2
area = (p * (p - a) * (p - b) * (p - c)) ** 0.5
print('⾯积: %f' % (area))
else:
print('不能构成三⻆形')
