[Python] Arts students 0 BASIC programming series two--basic concepts of data types, variables, constants

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(The syntax is different from Python, but the concepts and logic need to be understood), as an example of the most basic Excel VBA

3.1 Data:

In Excel, what you need to process and calculate is the data in Excel.

3.2 Data type:

collectively , the same type of data .

Depending on the nature of the data, it can be divided into different categories. Example: text, date, value, etc.

For different categories of data types , the computer stores it in different ways .

3.2.1 Data type: (VBA for Excel example)

1, byte type byte 1 byte save 0~255 Integer

2, integers integer 2 bytes save -32768~32767 integer

3, Long integer type long 4 bytes save -2147483648~2147483647 integer

4, single-precision floating-point 4 bytes

5, double-precision floating-point double 8 bytes

6. Currency type Currency 8 bytes

7, Decimal type decimal 14 bytes

8. String 10 bytes + String length/String length

9, Date-type Date 8 bytes

10, bool Boolean 2 bytes, save the result of logical judgment: TRUE or False

11. Variable Object 4 bytes

12. Variant Variant 16 bytes/22 bytes + string length

13. User-defined Type

3.2.2 Data type: (Python for example)

1, Number: integer int, floating-point float, boolean bool, complex complex

2, strings string

3. List

4, tuple tuple

5, Set sets

6. Dictionary Dictionary

 

※ Save containers of different data types :

In the face of different data types, when programming, you should tell the program what type of "container" is used to store the data to be processed .

　　　　constants and variables are the two "containers" that hold data.

No matter what type of data is stored, variables can be replaced, reused, and constants are not allowed.

3.3 Variables:

Variables are like containers,

Used to save data or objects that need to be temporarily saved while the program is running;

The values stored in the variable can be changed at any time.

3.3.1 Declaring variables: (defined under variables)

To save the data in a variable, you first need to declare the variables first.

Declaring variables: Use the VBA statement in Excel to specify the name of the variable and the type of data that can be stored.

Grammar:

Dim variable name as data type

Dim Str as String

Explain:

statement declares a variable of type string, named Str.

After declaring a variable, you can store the text string in str, but you cannot store the date, numeric value, or other type of data.

Other VBA syntax in Excel:

Dim variable name as data type → declare local variable

Private variable name as data type → declare module-level variable

Public variable name as data type → declare common variables

Static variable name as data type → declare static variable

Scope of the 3.3.2 variable: (the range used by the variable)

Determines which module or procedure the variable can be used in.

Local variable: scope individual procedure.

In a process of a program, the dim or static statement declares that the procedure for declaring a variable can be used.

Module-level variables: scoped individual modules.

Before the first procedure of a module, the dim or private statement declares that all procedures in the module are available.

Public variables: scope all modules.

Before the first procedure of a module, the public statement declares that all the modules in the project can be used.

3.3.3 Assigning values to variables: (storing data in variables)

3.3.3.1 assign values to variables of data types such as text, date, numeric, and so on.

Syntax: [let] variable name = data

Example: let str = "I love Excel" or str = "I love Excel"

3.3.3.2 assigning values to objects of type (object) variables such as worksheets, cells, etc.

Syntax: Set variable name = Object

Example: Set Rng = Worksheets (1). Rang ("A1")

3.4 Constants:

Constants are often used to store fixed values that are not modified, such as PI, personal income tax, and so on.

3.4.1 Declaration constants:

Specifies the name and data type of the constant, and assigns a value to the constant, and the value after the assignment cannot be re-assigned.

Syntax: Const variable name as data type = numeric

Example: Const p as single = 3.14

Scope of the 3.4.2 constant: (The range used by the constant)

Is the same as the scope of the variable.

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[Python] Arts students 0 BASIC programming series two--basic concepts of data types, variables, constants