定义: 只要条件成立,就一直循环执行循环代码
机构:
while 条件:
循环执行代码
else:
执行代码2
例如:
while True:
print('0-0')
该函数则无限循环打印'0-0',直至天荒地老!
指令:break(推出本层循环)
continue(推出本次循环)
二格式化输出
占位符:% ( %d,占位指定取数值,%s: 占位指定取字符串,%r : 占位还原取值函数)
三 运算
python里面包含数学运算(如= - * / ),逻辑运算(and,or,not) 比较运算( == , <= ,<= 等)
and 并且。 左右两端同时为真。 结果才能是真
or 或者。 左右两端有一个是真。 结果就是真 not 非真即假， 非假即真x or y -> ( 如果x为0,取y,否则取x)
x and y (如果x为0,则取X,否则取y)
运算顺序: () > not > and > or
编码:
最早的计算机编码:ASCII 占8位
中国:
GBK : 占16位最早的万国码: unicode 占 32位
UTF-8: 可变长万国码,占位最短8位
UTF-16: 可变长万国码,占位最短16位
UTF-32: 可变长万国码,占位最短32位
print(1>1 or 3<4 or 4>5 and 2>1 and 9>8 or 7<6) #True print(not 2 > 1 and 3 < 4 or 4 > 5 and 2 > 1 and 9 > 8 or 7 < 6 ) #false print(8 or 3 and 4 or 2 and 0 or 9 and 7 ) #8 print(0 or 2 and 3 and 4 or 6 and 0 or 3 ) #4 print(6 or 2 > 1) #6 print(3 or 2 > 1) #3 print(0 or 5 < 4 ) # False print(5<4 or 3) #3 print(2>1 or 6) # true print(3 and 2>1) # 3 print(0 and 3>1) # 0 print(2>1 and 3) # 3 print(3>1 and 0) # 0 print(3>1 and 2 or 2<3 and 3 and 4 or 3>2) #2 while 条件: 执行代码1 else: 执行代码2 guess_num = int(input('请猜测幸运数字:')) while guess_num != 66: if guess_num > 66: print('猜大了!') guess_num = int(input('请猜测幸运数字:')) elif guess_num < 66: print('猜小了!') guess_num = int(input('请猜测幸运数字:')) else: print('You are right !') guess_num = int(input('请输入正确的数字:')) count = 1 while guess_num != 66: if count ==3: print('Your are stupid !') break elif guess_num > 66: print('猜大了!') elif guess_num <66: print('猜小了!') elif guess_num == 66: break print('Your are right!') count += 1 guess_num = int(input('请输入正确的数字:')) else: print('You are right !') num = 1 while num <= 10: if num != 7: print(num) num = num + 1 count = 1 while count <10: count += 1 if count == 7: continue print(count) sum = 0 count = 1 while count <= 100: sum += count count +=1 print(sum) count = 1 while count <=50: print(count * 2 -1) count +=1