For formatting output, and code string

1. The format of the output string

• % :Placeholder
  • % S: string
  • And% d% i: Integer
  • %%: Escape become common%
• % (): Number of data inside the brackets no more and no less, must correspond
• f "{} '': the contents of the braces are generally put variable, if you want to put a string, you need to use single quotes # Python3.6 and above to use this feature

2. while loop

• while keyword criteria: infinite loop #

  Loop

• Conditions Terminator Cycle

  • break: terminate the current cycle
  • continue: out of this cycle, the next cycle continues
  • exit (0): terminates the current program

3. Operator

• Arithmetic Operators

  • + - * / #   加减乘除
    **          #幂
     print(2 ** 4)
    //          #整除
    print(5 // 2)
    %           #取余（模）
    print(5 % 2)

• Assignment Operators

  • a = 1
    a += 1  # a = a + 1
    a -= 1  # a = a - 1
    a *= 1  # a = a * 1
    a /= 1    # a = a / 1
    a **= 1   # a = a ** 1
    a %= 1    # a = a % 1

• Logical Operators

  • and (与) #和
    or (或)
    not (非) # 不是
    1 and 0  # and是两边都是真的时候才是真，只要有一边是假就取假
    0 and 1
    print(1 and 9)   #and 运算 两边都是真的时候取and后边的内容
    print(False and 0) #and 运算 两边都是假的时候取and前边的内容
    print(3 > 2 and 9)  #3>2 视为一个整体来看
    print(1 or 0)  # 只要有一个是真就取真
    print(0 or 1)
    print(1 or 4)   # or 两个都是真的时候，取or前面的内容
    print(False or 0) # or 两个都是假的时候，取or后面的内容

• Comparison Operators

  • 等于  ==
    不等于 !=
    大于 >
    小于 <
    大于等于 >=
    小于等于 <=

• Member operator

  • is  是
    is not 不是
    is 判断是不是同一个
    == 判断是不是长得一样

4. encoding

• ASCII code: does not support Chinese

• GBK: GB

  • English one byte
  • Chinese 2 bytes

• Unicode: Unicode

  • English 2 bytes
  • 4 Chinese characters

• utf-8: Unicode-based, it is now the most popular encoding, with at least one byte

  • English one character
  • European two characters
  • Asian 3 characters

• utf-16: with a minimum of 2 bytes

• Unit Conversion

  • 1 byte = 8 # most important

  • 1Byte = 8bit

  • 1024KB = 1MB

    ...