Python基础之输出格式和If判断

格式化输出的三种方式

一、占位符

#占位符
name = 'nick'
age = 19 
print('my name is %s my age is %s' % (name, age))

age = 19
print('my name is %d' % age)

my name is nick my age is 19

my age is 19

二、format格式化

name = 'nick'
age = 19

print("Hello, {}.You are {}.".format(age, name))
print("Hello, {1}. You are {0}-{0}".format(age, name))
print("Hello, {name}. You are {age}-{age}.".format(age = age, name = name))

Hello，nick. You are 19.

Hello，nick. You are 19-19

Hello，nick. You are 19-19.

三、f-String格式化

name = "nick"
age = 19
print(f'Hello, {name}. You are {age}.')
pint(F'Hello, {name}. You are {age}.')

print(f'{age*2}')

salary = 6.66666
print(f'{salary:.2f}')

Hello, nick. You are 19.

6.67

横向输出是在print中加一个参数end=' '

流程控制之if判断

一、语法

# if

cls = 'human'
gender = 'female'
age = 19

if cls == 'human' and gender == 'female' and age > 16 and age a < 22:
	print('开始表白')
	
print('end....')


# if...else

cls = 'human'
gender = 'female'
age = 38

if cla == 'human' and gender == 'female' and age > 16 and age < 22:
	print('开始表白')
else:
	print('阿姨好')
	
# if...elif...else

cls = 'human'
gender = 'female'
age = 28

if cls == 'human' and gender == 'female' and age > 16 and age < 22:
	print('开始表白')
elif cls == 'human' and gender == 'female' and age > 22 and age < 30:
	print('考虑下')
else：
	print('阿姨好')

开始表白

end…..

阿姨好

考虑下

二、if的嵌套

cls = 'human'
gender = 'female'
age = 19
is_successful = False

if cls == 'human' and gender == 'female' and age > 16 and age < 22:
	print('开始表白')
	if is_successful:
		print('那我们一起走吧。。。')
	else:
		print('我逗你玩呢')
else:
	print('阿姨好')

开始表白

我逗你玩呢

练习

练习一：成绩评判

如果成绩>=90，打印"优秀"
如果成绩>=80 并且成绩<90，打印"良好"
如果成绩>=70 并且成绩<80，打印"普通"
其他情况：打印"差"

# 成绩评判
score = input("your score: ")
score = int(score)

if score >= 90:
    print('优秀')
elif score >= 80:
    print('良好')
elif score >= 70:
    print('普通')
else:
    print('差')

your score: 80
良好

练习二：模拟登录注册

#模拟登录注册
user_from_db = 'nick'
pwd_from_db = 123

user_from_inp = input('username:')
pwd_from_inp = input('password: ')

if user_from_inp == user_from_db and pwd_from_inp == pwd_from_db:
    print('login successful')
else:
    print('username or password error')

username: nick
password: 123
username or password error