文章目录

Exercise 26. Congratulations, Take a Test!Exercise 27. Memorizing LogicExercise 28. Boolean PracticeExercise 29. What IfExercise 30. Else and If

Exercise 26. Congratulations, Take a Test!

这是一个改正别人代码的测试，挺好玩的。大家可以去网站上http://learnpythonthehardway.org/python3/exercise26.txt下载源码，自己改一改，多用用编译器帮你找找错误。 我改了一版，放在这里，大家可以对一对哈：

print("How old are you?", end=' ') age = input() print("How tall are you?", end=' ') height = input() print("How much do you weigh?", end=' ') weight = input() print(f"So, you're {age} old, {height} tall and {weight} heavy.") from sys import argv script, filename = argv txt = open(filename) print(f"Here's your file {filename}:") print(txt.read()) print("Type the filename again:") file_again = input("> ") txt_again = open(file_again) print(txt_again.read()) print('Let\'s practice everything.') print("""You\'d need to know \'bout escapes with \\ that do \n newlines and \t tabs.""") poem = """ \tThe lovely world with logic so firmly planted cannot discern \n the needs of love nor comprehend passion from intuition and requires an explanation \n\t\twhere there is none. """ print("--------------") print(poem) print("--------------") five = 10 - 2 + 3 - 6 print(f"This should be five: {five}") def secret_formula(started): jelly_beans = started * 500 jars = jelly_beans / 1000 crates = jars / 100 return jelly_beans, jars, crates start_point = 10000 beans, jars, crates = secret_formula(start_point) # remember that this is another way to format a string print("With a starting point of: {}".format(start_point)) # it's just like with an f"" string print(f"We'd have {beans} beans, {jars} jars, and {crates} crates.") start_point = start_point / 10 print("We can also do that this way:") formula = secret_formula(start_point) # this is an easy way to apply a list to a format string print("We'd have {} beans, {} jars, and {} crates.".format(*formula)) people = 20 cats = 30 dogs = 15 if people < cats: print("Too many cats! The world is doomed!") if people > cats: print("Not many cats! The world is saved!") if people < dogs: print("The world is drooled on!") if people > dogs: print("The world is dry!") dogs += 5 if people >= dogs: print("People are greater than or equal to dogs.") if people <= dogs: print("People are less than or equal to dogs.") if people == dogs: print("People are equal to dogs.")

对了庆祝一下过半啦，基础知识讲完了，该将判断，循环等结构啦，加油！！！

Exercise 27. Memorizing Logic

这一节主要讲的是真值表，学过布尔代数的与或非运算的朋友就不需要再看啦！！！

Exercise 28. Boolean Practice

这一节是让大家在python交互式环境中体验了一下布尔表达式，也没什么特别需要注意的。

Exercise 29. What If

这一节只是一个判断的初步探索，第30个练习讲的if和else

Exercise 30. Else and If

这一节讲的是elif块的应用，也挺简单的，例程如下：

people = 30 cars = 40 trucks = 15 if cars > people: print("We should take the cars.") elif cars < people: print("We should not take the cars.") else: print("We can't decide.") if trucks > cars: print("That's too many trucks.") elif trucks < cars: print("Maybe we could take the trucks.") else: print("We still can't decide.") if people > trucks: print("Alright, let's just take the trucks.") else: print("Fine, let's stay home then.")