循环(while,for)

Posted 2021-01-31 study-notes-of-python

2019-01-01

一、while循环

标准格式如下：

count = 0
while True:
    print("count:",count)
    count = count +1   相当于count +=1

例子：

age_of_oldboy = ‘56‘

count = 0
while True :
    if count == 3:
        break
    guss_age = input("guss the age:")
    if guss_age == age_of_oldboy :
        print("yes,you got it.")
        break
    elif guss_age > age_of_oldboy :
        print("please guss smaller.")
    else:
        print("please guss bigger.")
    count +=1
if count ==3
    print("you have tried so many times ,you lose.")

可以精简代码如下：

count = 0
while count < 3:
    guss_age = input("guss the age:")
    if guss_age == age_of_oldboy :
        print("yes,you got it.")
        break
    elif guss_age > age_of_oldboy :
        print("please guss smaller.")
    else:
        print("please guss bigger.")
    count +=1
else:
    print("you have tried so many times ,you lose.")

二、for循环
标准格式如下：

‘‘‘
                        0,1,2,3,4,5,6,7,8,9
for i in range(10):   每循环一次取一个值
    print("loop ",i)
‘‘‘
‘‘‘
                          0,3,6,9
for i in range(0,10,3):   每循环一次隔两个跳一个值（3-1）
    print("loop ",i)
‘‘‘

例子：

age_of_oldboy = 56
for i in range(3):
    guess_age = int(input("guess age:"))
    if guess_age == age_of_oldboy:
        print("yes,you got it.")
        break
    elif guess_age > age_of_oldboy:
        print("please guess smaller.")
    else:
        print("please guess smaller.")
else:
    print("you have tried too many times.you lose!")

三、while进阶
用户可以选择性循环

age_of_oldboy = 56
count = 0
while count < 3:
    guss_age = input("guss the age:")
    if guss_age == age_of_oldboy :
        print("yes,you got it.")
        break
    elif guss_age > age_of_oldboy :
        print("please guss smaller.")
    else:
        print("please guss bigger.")
    count +=1
    if count ==3:
        countine_confirm = input("do you want to keep guessing...")
        if countine_confirm != ‘n‘:
            count = 0
#else:
#    print("you have tried so many times ,you lose.")

四、循环套循环

for i in range(10):
    print(‘--------‘,i)
    for j in range(10):
        print(j)
        if j >2:
            break
    if i >2:
        break