python学习---for循环

for循环的最基本用法

for i in range(10):   # 这里指循环10次
    print("loop:",i)

运行结果，如图

将上节课的while循环，修改为for循环，如

count = 0
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("think smaller....")
    else:
        print("think bigger...")
else:
    print("you have tried too many times....")

运行结果，如图：

 如果在for循环中想实现隔2个打印一个，比如要打印0 2 4 6 8 ，如何实现呢

for i in range(0,10,2)  # 注意这里的2指的就是步长，代表的是中间隔2个数
    print("loop:",i)  

运行结果，如图

升级while循环，如果输入3次，循环是否继续

count = 0
age_of_oldboy = 56

while count < 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("think smaller...")
    else:
        print("think bigger...")
    count = count+1
    if count == 3:
        countine_confirm = input("do you want to keep guessing...")
        if countine_confirm != "n":
            count = 0

 for循环与continue的结合使用

continue是跳出本次循环，进入下个循环，break是结束当前循环

for i in range(10):
    print("---", i)
    if i > 5:
        continue  # continue是跳出本次循环，进入下个循环
    print("zwt")

运行结果，如图

 for循环与break的结合使用

for i in range(10):
    print("---", i)
    for j in range(10):
        print(j)
        if j > 5:
            break   # 注意此处的break是结束本次循环，也就是只结束内层循环，外层循环不受影响

运行结果，如图