python-while循环

while True

一直循环

age_of_oldboy = 56
while True:
    guess_age = int(input("guess_age:"))
    if guess_age == age_of_oldboy:
        print("yes,you got it.")
    elif guess_age > age_of_oldboy:
        print("think smaller...")
    else:
        print("think bigger!")

猜对了停止

例1:

age_of_oldboy = 56
while True:
    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!")

例2：只给3次机会猜，猜对了退出

age_of_oldboy = 56
count = 0
while True:
    if count == 3:
        break
    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 +=1

while 条件
定义一个变量
while 判断条件(变量的判断)
    如果判断条件满足执行的代码
    对变量的值进行修改
    
不可以停止的循环(判断条件一直满足) 称之为死循环

age_of_oldboy = 56
count = 0
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 += 1

while 条件 else

i = 0
while i < 5:
    print(i)
    if i == 2:
        break
    i += 1
else:
    print("else")   #while循环中的break执行 else中的代码将不会执行

age_of_oldboy = 56
count = 0
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 +=1
else:
    print("you have tried too many times...!")

while嵌套

while 条件1：

    条件1满足时，做的事情1

    条件1满足时，做的事情2

    条件1满足时，做的事情3

    ......

   while 条件2：

        条件2满足时，做的事情1

        条件2满足时，做的事情2

        条件2满足时，做的事情3

        ......

"""
*
**
***
****
*****
"""
# 在默认的情况下 使用print 默认打印完成后 会有一个换行
# print("哈哈") 完整的格式 print("哈哈", end="
")
# 定义一个变量 记录行数
row = 1
while row <= 5:
    # 定义一个变量 记录列数
    col = 1
    while col <= row:
        print("*", end="")
        col += 1
    # 换行
    print()
    row += 1

# 九九乘法表
# 定义一个变量 记录行数
# %2d 显示两位 如果只有一位 使用空格占位 默认为右对齐
# 如果左对齐 就是 %-2d
x = 1
while x <= 9:
    # 定义一个变量 记录列数
    y = 1
    while y <= x:
        print("%d * %d = %-2d" % (y, x, x * y), end="  ")
        y += 1
    # 换行
    print()
    x += 1

完