Python 学习笔记【05】流程控制

　　If...Else

 1 _username = "A1_Code"
 2 _password = "123"
 3 
 4 username = input("username:")
 5 password = input("password:")
 6 
 7 if _username == username and _password == password:
 8     print("Welcome user {name} login...".format(name=username))
 9 else:
10     print("Invalid username or password!")

　　If...Elif...Else

1 age_of_oldboy = 56
2 guess_age = int(input("guess age:"))
3 
4 if guess_age == age_of_oldboy:
5     print("yes,you got it.")
6 elif guess_age > age_of_oldboy:
7     print("think smaller...")
8 else:
9     print("think bigger!")

　　while

1 count = 0
2 while True:
3     print("count:", count)
4     count = count + 1 #count+=1

　　Break 跳出循环

1 count = 0
2 while True:
3     print("count:", count)
4     count = count + 1 #count+=1
5     if count == 1000:
6         break

　　加计数器

 1 age_of_oldboy = 56
 2 
 3 count = 0
 4 while True:
 5     if count == 3:
 6         break
 7     guess_age = int(input("guess age:"))
 8     if guess_age == age_of_oldboy:
 9         print("yes,you got it.")
10         break
11     elif guess_age > age_of_oldboy:
12         print("think smaller...")
13     else:
14         print("think bigger!")
15 
16     count += 1

　While 后加条件

 1 age_of_oldboy = 56
 2 
 3 count = 0
 4 while count < 3:
 5     if count == 3:
 6         break
 7     guess_age = int(input("guess age:"))
 8     if guess_age == age_of_oldboy:
 9         print("yes,you got it.")
10         break
11     elif guess_age > age_of_oldboy:
12         print("think smaller...")
13     else:
14         print("think bigger!")
15 
16     count += 1

　　While...Else

 1 age_of_oldboy = 56
 2 
 3 count = 0
 4 while count < 3:
 5     if count == 3:
 6         break
 7     guess_age = int(input("guess age:"))
 8     if guess_age == age_of_oldboy:
 9         print("yes,you got it.")
10         break
11     elif guess_age > age_of_oldboy:
12         print("think smaller...")
13     else:
14         print("think bigger!")
15     count += 1
16 else:
17     print("you have tried too many times...fuck off")

　　For

1 for i in range(10):
2     print("loop", i)

　　For...Else

 1 age_of_oldboy = 56
 2 
 3 for i in range(3):
 4     guess_age = int(input("guess age:"))
 5     if guess_age == age_of_oldboy:
 6         print("yes,you got it.")
 7         break
 8     elif guess_age > age_of_oldboy:
 9         print("think smaller...")
10     else:
11         print("think bigger!")
12 else:
13     print("you have tried too many times...fuck off")

　　For 跳跃循环

1 for i in range(0, 10, 2):
2     print("loop", i)

　　优化

 1 age_of_oldboy = 56
 2 
 3 count = 0
 4 while count < 3:
 5     if count == 3:
 6         break
 7     guess_age = int(input("guess age:"))
 8     if guess_age == age_of_oldboy:
 9         print("yes,you got it.")
10         break
11     elif guess_age > age_of_oldboy:
12         print("think smaller...")
13     else:
14         print("think bigger!")
15     count += 1
16     if count == 3:
17         countine_confirm = input("Do you want to keep guessing..?")
18         if countine_confirm != 'n':
19             count = 0

　　加断点 Debug

　　Continue 跳出本次循环，继续下次循环；Break　结束循环

1 for i in range(0, 10):
2     if i < 3:
3         print("loop", i)
4     else:
5         continue
6     print("hehe...")

　　循环套循环

1 for i in range(10):
2     print('----------', i)
3     for j in range(10):
4         print(j)
5         if j > 5:
6             break

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原文地址：https://www.cnblogs.com/a1-code/p/6000185.html