习题 2:注释和 # 号
# A comment, this is so you can read your program later. # Anything after the # is ignored by python. print("I could have code like this.") # and the comment after is ignored # You can also use a comment to "disable" or comment out a piece of code: # print("This won't run.") print("This will run.")
习题 3:数字和数学计算
print("I will now count my chickens:") 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("Is it 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)
习题 4:变量和命名
cars = 100 space_in_a_car = 4.0 drivers = 30 passengers = 90 cars_not_driven = cars - drivers cars_driven = drivers carpool_capacity = cars_driven * space_in_a_car average_passengers_per_car = passengers / cars_driven print("There are", cars, "cars available.") print("There are only", drivers, "drivers acailable.") print("Thers will be", cars_not_driven, "empty cars today.") print("We can transport", carpool_capacity, "people today.") print("We have", passengers, "to carpool today.") print("We need to put about", average_passengers_per_car, "in each car.")
习题 5:更多的变量和打印
my_name = 'Zed A. Shaw' my_age = 35 # not a lie my_height = 74 #inches my_weight = 180 # lbs my_eyes = 'Blue' my_teeth = 'White' my_hair = 'Brown' print("Let's talk about %s." % my_name) print("He's %d inches tall." % my_height) print("He's %d pounds heavy." % my_height) print("Actually that's not too heavy.") print("He's got %s eyes and %s hair." % (my_eyes, my_hair)) print("His teeth are usually %s depending on the coffee." % my_teeth) # this line is tricky, try to get it exactly right print("If I add %d, %d, and %d Iget %d." % (my_age, my_height, my_weight, my_age + my_height + my_weight))
Python 格式化字符:
%c 格式化字符及其ASCII码 %s 格式化字符串 %d 格式化整数 %u 格式化无符号整型 %o 格式化无符号八进制数 %x 格式化无符号十六进制数 %X 格式化无符号十六进制数(大写) %f 格式化浮点数字,可指定小数点后的精度 %e 用科学计数法格式化浮点数 %E 作用同%e,用科学计数法格式化浮点数 %g %f和%e的简写 %G %f 和 %E 的简写 %p 用十六进制数格式化变量的地址