if、while、for循环
if 条件1: 结果1 elif 条件2: 结果2 elif 条件3; 结果3 else: 结果4
while循环
while 条件:
执行语句 if 条件1:
结果1
elif 条件2:
break #终止循环
结果0
while 条件:
执行语句
if 条件1:
结果1
elif 条件2:
continue #符合条件2时不执行结果0
结果0
九九乘法表
num2 = 1 while num2<=9: num1 = 1 while num1<=num2: print(num1,"*",num2,"=",num1*num2,end=" ") num1+=1 print() num2+=1
for循环
flag = False for i in range(3): username = input("Username:") password = input("Password:") if username == "rjw" and password =="123456": flag = True break else: print("try again") if not flag: print("账户已锁定")
else作用(循环正常结束后,才会执行)
# flag = False for i in range(3): username = input("Username:") password = input("Password:") if username == "rjw" and password =="123456": # flag = True break else: print("try again") else: print("账户已锁定")