Python Foundation _0623

Named rules:

Project name Package name python file name

1. Cannot start with a number, cannot use Chinese

2. Cannot use keywords

3. English Letter Test_06_23

4. Alphanumeric underline (cannot start with a number)

5. See the name of knowing age

Variable:

x = 1 #定义一个变量x, and is assigned a value of 1

Print (x) #如果要引用某个变量 to ensure that the variable has been assigned a defined value

Common data types: shaping floating-point Boolean strings

age = #关键字 int

Score = 99.9 #浮点数 decimal key float

True #关键字 Boolean bool True False

False

String:

Content keyword in pairs of single or paired double quotes: str

Age = ' 20 '

Print (' X ')

Some special uses of strings:

A = ' Hello '

b = ' World '

c = 6

Concatenation of strings ' + ', "+" data types should be the same

String with other data types to do splicing coercion and then use ' + '

Forced conversion str (variable name/variable value)

Print (A+str (c))

', ', using a comma to output the result will be ordered an obvious space, string with other data types to be spliced

The slice value of the string (take left without right)

z = ' Hello '

The index of the string is starting from 0

Single String value: String variable name [index position]

Print (z[1]) E

Multiple string values: string variable name [where the character index begins: where the character index ends +1]

Print (Z[1:4]) ell

The character index ends where +1 has no bounds, so it can cross over

Print (Z[1:10]) Ello

Reverse order:

Print (z[-5:-3]) he

Last value: Print (Z[-1])

Formatted output:

Age = 18

Sex = ' female '

Print (' Lucy is %s years old, ' % of age ')

Print (' Lucy is%s years old, she's a%s ' % (age, Sex))

Print (' Lucy is {} years old '. Format (age))

Print (' Lucy is {0} years old, she's a {1} '. Format (age, Sex)

Placeholder:%s%f%d

Python Foundation _0623