Language type:
One: Interpretation type: from top to bottom line by line interpretation converted into binary
Advantages: fast development efficiency, cross-platform.
Disadvantage: slow execution
Compiled: All compiled and converted into binary from top to bottom
Disadvantages: slow development efficiency, not cross-platform.
Advantages: fast execution
Two: python types
cpython jpython other languages python
Three: python version (2.7/3)
Difference between python2 and python3:
One: a lot of repetitive code in python2, and other language bad habits.
python3 is simple, beautiful and clear
Two: python2 prints without parentheses, python3 prints with parentheses
Four: Variables:
Rules: 1 Variables consist of any combination of numbers, letters, and underscores
2 cannot start with a number
3 cannot be a keyword in python
4 Variables are descriptive
5 cannot be Chinese
6 Camel case and underline
7 Variable names should not be too long
Five: Constants: Constants that will not change all the time, such as the founding date, festivals
Six: User interaction: input
Three logins:
count=0 while count<3: count = count + 1 name = input('>>>Please enter your username') password = input('>>>Please enter your password') if name=='zhujun'and password=='12345678': print ('Login successful') break else: print('Please re-enter')
Seven: Notes
Single line comment: #
Multi-line comments: '''' or """"
Eight: if conditional statement
if condition:
result
if and else collocation
if/elif/elif/else
Nine: while loop
Small exercise:
1. Use the while loop to input 1 2 3 4 5 6 8 9 10 count=0 while count<10: count=count+1 if count==7: print('') continue else:print(count) 2. Find the sum of all numbers from 1 to 100 count=1 sum=0 while count<101: sum=sum+count count=count+1 print(sum) 3. Output all odd numbers within 1-100 count=0 while count<101: count=count+1 if count % 2 == 1: print(count) 4. Output all even numbers within 1-100 count = 0 while count < 101: count = count + 1 if count % 2 == 0: print(count) 5. Find the sum of all numbers 1-2+3-4+5 ... 99 The first: count=1 sum=0 while count<100: if count%2==0: sum=sum-count count = count + 1 else: sum=sum+count count = count + 1 print(sum) #The second: sum=0 for i in range(1,100): if i %2==0: sum=sum-i else: i % 2 == 1 sum = sum + i
print(sum)
Sum of all odd and even numbers from 1 to 100 print(sum([i for i in range(101) if i%2==0])) print(sum([i for i in range(101) if i%2==1]))