流程控制——while循环

1、语法1：
while 条件:
　　代码1
　　代码2
　　代码3

while True:
    name=input('please input your name: ')
    pwd=input('please input your password: ')

    if name == 'egon' and pwd == '123':
        print('login successful')
    else:
        print('username or password error')

2、结束while循环的两种方式　　

方式一：条件改为False，
在条件改为False时不会立即结束掉循环，而是要等到下一次循环判断条件时才会生效

 tag=True
    while tag:
        name=input('please input your name: ')
        pwd=input('please input your password: ')
    
        if name == 'egon' and pwd == '123':
            print('login successful')
            tag=False
        else:
            print('username or password error')
    
        print('===>')

方式二：while+break
break一定要放在循环体内，一旦循环体执行到break就会立即结束本层循环

    while True:
        name=input('please input your name: ')
        pwd=input('please input your password: ')
    
        if name == 'egon' and pwd == '123':
            print('login successful')
            break
        else:
            print('username or password error')
    
        print('===>>>>>')
        print('===>>>>>')

while+continue:结束本次循环，直接进入下一次循环

# 示例一
count=1
while count < 6: #count=6
    if count == 4:
        count += 1
        continue
        
    print(count)
    count+=1

# 示例二：
while True:
    name=input('please input your name: ')
    pwd=input('please input your password: ')

    if name == 'egon' and pwd == '123':
        print('login successful')
        break
    else:
        print('username or password error')
        # continue # 此处加continue无用