Python Concise Tutorial Learning Notes

1. use three quotation marks ( "" or "" ")

Using the three quotes, you can indicate a multiline string. You can use single and double quotation marks freely in three quotes. For example:

str= "This is a multi-line string. the first line.
The second line.
"What ' s your name?," I asked.
He said "Bond, James bond."
" "

2. Natural string

If you want to indicate certain strings that do not require special handling such as escape characters (invalid escape symbols), then you need to specify a natural string. Natural strings are specified by prefixing r or specifying the string R . such as str= r"Newlines are indicated by \n" .

The print (str) result is:newlines is indicated by \ n.

Be sure to use a natural string to process the regular expression. Otherwise, you will need to use a lot of back slashes. For example, a forward reference can be written as ' \\1 ' or R ' \1 '.

3. The string is immutable

This means that once you create a string, you can no longer change it.

4. string literals by literal meaning

If you put two strings next to each other by literal means , they will be automatically connected by Python. For example, ' what\ ' s '   your Name? ' " What ' s    your name? "

5. Object

6. Variable

7. Logical lines and physical lines

If you want to use more than one logical line in a physical line, you need to use a semicolon (;) to specifically indicate this usage. semicolon represents the end of a logical line/statement. For example: I=5;print (i)

Example of writing a logical line in multiple physical rows. It is called the Explicit row connections

s =  " is a string. \
This continues the string. '
print ( s)

输出结果为：This is a string. This continues the string.

在逻辑行中使用了圆括号、方括号或波形括号的时候，也可以使多个物理行对应一个逻辑行，这被称为暗示的行连接。


str=[1,23,"hello"
,"ok"]
print(str)


结果为：[1, 23, ‘hello‘, ‘ok‘]




Python Concise Tutorial Learning Notes