Python书籍示例代码(第四章)

《Python语言程序设计基础（第2版）》嵩天著

第四章

●4 - 1
PM2
.5
空气质量提醒(1)

PM = eval(input("请输入PM2.5数值: "))
if 0 <= PM < 35:
    print("空气优质，快去户外运动!")
if 35 <= PM < 75:
    print("空气良好，适度户外活动！")
if 75 <= PM:
    print("空气污染，请小心！")
●4 - 2
PM2
.5
空气质量提醒(2)

PM = eval(input("请输入PM2.5 数值: "))
if PM >= 75:
    print("空气存在污染，请小心！")
else:
    print("空气没有污染，可以开展户外运动!")
● 4 - 3
PM2
.5
空气质量提醒(3)

PM = eval(input("请输入PM2.5数值: "))
if 0 <= PM < 35:
    print("空气优质，快去户外运动!")
elif 35 <= PM < 75:
    print("空气良好，适度户外活动！")
else:
    print("空气污染，请小心！")
●4 - 4
身体质量指数BMI的计算(1)

# e5.1CalBMI.py
height, weight = eval(input("请输入身高(米)和体重(公斤)[逗号隔开]: "))
bmi = weight / pow(height, 2)
print("BMI 数值为：{:.2f}".format(bmi))
wto, dom = "", ""
if bmi < 18.5:  # WTO 标准
    wto = "偏瘦"
elif bmi < 25:  # 18.5 <= bmi < 25
    wto = "正常"
elif bmi < 30:  # 25 <= bmi < 30
    wto = "偏胖"
else:
    wto = "肥胖"
if bmi < 18.5:  # 我国卫生部标准
    dom = "偏瘦"
elif bmi < 24:  # 18.5 <= bmi < 24
    dom = "正常"
elif bmi < 28:  # 24 <= bmi < 28
    dom = "偏胖"
else:
    dom = "肥胖"
print("BMI 指标为:国际'{0}', 国内'{1}'".format(wto, dom))
●4 - 5
身体质量指数BMI的计算(2)

# e5.2CalBMI.py
height, weight = eval(input("请输入身高(米)和体重(公斤)[逗号隔开]: "))
bmi = weight / pow(height, 2)
print("BMI 数值为：{:.2f}".format(bmi))
wto, dom = "", ""
if bmi < 18.5:
    wto, dom = "偏瘦", "偏瘦"
elif 18.5 <= bmi < 24:
    wto, dom = "正常", "正常"
elif 24 <= bmi < 25:
    wto, dom = "正常", "偏胖"
elif 25 <= bmi < 28:
    wto, dom = "偏胖", "偏胖"
elif 28 <= bmi < 30:
    wto, dom = "偏胖", "肥胖"
else:
    wto, dom = "肥胖", "肥胖"
print("BMI 指标为:国际'{0}', 国内'{1}'".format(wto, dom))
● 4 - 6
蒙特卡罗方法求解π值

# e6.1CalPi.py
from random import random
from math import sqrt
from time import clock

DARTS = 1000
hits = 0.0
clock()
for i in range(1, DARTS + 1):
    x, y = random(), random()
    dist = sqrt(x ** 2 + y ** 2)
    if dist <= 1.0:
        hits = hits + 1
pi = 4 * (hits / DARTS)
print("Pi值是{}.".format(pi))
print("运行时间是: {:5.5}s".format(clock()))
●4 - 7
异常处理的小例子(1)

try:
    num = eval(input("请输入一个整数: "))
    print(num ** 2)
except NameError:
    print("输入错误，请输入一个整数!")
4 - 8
异常处理的小例子(2)

try:
    alp = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    idx = eval(input("请输入一个整数: "))
    print(alp[idx])
except NameError:
    print("输入错误，请输入一个整数!")
except:
    print("其他错误")
●4 - 9
异常处理的小例子(3)

try:
    alp = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    idx = eval(input("请输入一个整数: "))
    print(alp[idx])
except NameError:
    print("输入错误，请输入一个整数!")
else:
    print("没有发生异常")
finally:
    print("程序执行完毕，不知道是否发生了异常")