Learn Python the Hard Way 5: Ex03 Numbers and Math

5 Ex03 Numbers and Math

很多编程语言中, 运算符是必不可少的. (当当当… 数学课)

5.1 运算符

+

plus 加

-

minus 减

/

slash 斜杠(取商)

*

asterisk 星号(乘)

%

percent 百分号(取余)

<

less-than 小于

>

greater-than 大于

<=

less-than-equal 小于等于

>=

greater-than-equal 大于等于

# -*- coding: utf-8 -*
print "Hens", 25 + 30 / 6
print "Roosters", 100 - 25 * 3 % 4

print "Now I will count the eggs:"

print 3 + 2 + 1 - 5 + 4 % 2 - 1 / 4 + 6

print "It's true that 3 + 2 < 5 - 7?"

print 3 + 2 < 5 - 7

print "what is 3 + 2?", 3 + 2
print "What is 5 - 7?", 5 - 7

print "Oh, that's why it's false."

print "How about some more."

print "Is it greater?", 5 > -2
print "Is it greater or equal?", 5 >= -2
print "Is it less or equal?", 5 <= -2

这是你应该要看到的输出:

5.2 研究学习

请解释每一行运算符是如何工作的.

重写整个程序,请需要的地方使用浮点类型数据.

# -*- coding: utf-8 -*
print "Hens", 25 + 30 / 6
#取商/优先级高于+,先算 30 / 6, 然后25 + 5 = 30
print "Roosters", 100 - 25 * 3 % 4
#*和取余%优先级高于-, 先算25 * 3 = 75, 然后75 / 4 = 13余3,所以75 % 4 = 3, 最后算100 - 3 = 97
print "Now I will count the eggs:"

print 3 + 2 + 1 - 5 + 4 % 2 - 1 / 4 + 6
#先算4 % 2 = 0 然后算 1 / 4 = 0, 然后从做到右3 + 2 + 1 - 5 + 0 - 0 + 6 =  7
print "It's true that 3 + 2 < 5 - 7?"
print 3 + 2 < 5 - 7
#先算 3 + 2 = 5, 然后算 5 - 7 = -2, 最后计算逻辑 5 < -2
print "what is 3 + 2?", 3 + 2 #3 + 2 = 5
print "What is 5 - 7?", 5 - 7 #5 - 7 = -2

print "Oh, that's why it's false."
print "How about some more."
#下面均是逻辑运算,输出真(True)或假(False)
#注意Python中的真假Ture,False需要大写首字母
print "Is it greater?", 5 > -2
print "Is it greater or equal?", 5 >= -2
print "Is it less or equal?", 5 <= -2

# -*- coding: utf-8 -*
print "Hens", 25.0 + 30.0 / 6.0
print "Roosters", 100.0 - 25 * 3 % 4

print "Now I will count the eggs:"

print 3 + 2 + 1 - 5 + 4 % 2 - 1.0 / 4.0 + 6 #这里需要用浮点型

print "It's true that 3 + 2 < 5 - 7?"

print 3 + 2 < 5 - 7

print "what is 3 + 2?", 3 + 2
print "What is 5 - 7?", 5 - 7

print "Oh, that's why it's false."

print "How about some more."

print "Is it greater?", 5 > -2
print "Is it greater or equal?", 5 >= -2
print "Is it less or equal?", 5 <= -2