04-c Language data types

Learning Focus:

• variables, constants, constant variables, identifiers
• Basic data types

1. Constants are divided into: integer constants, implementation constants, character constants, string constants, symbolic constants, character constants are divided into: ordinary characters, escape characters.

2. Variable: A variable represents a storage unit with a name and a specific attribute. Has attributes that must be defined first and then used. Variable is a name of the storage address, from the variable value, the actual is to find the corresponding memory address through the variable name, from the storage unit to read data.

3. Constant variables: With the basic properties of the variable, there is a type, the storage unit, but the variable is not allowed to change its value during the existence. A constant variable is a non-variable with a name, which is a invariant without a name.

Definition of constant variable: const float pi=3.1415926;

Definition of Symbolic constants: #define PI 3.1415926;

4. Identifier: In a high-level computer language, a valid sequence of characters used to name variables, symbolic constant names, functions, types, and so on are collectively known as identifiers

Core of programming language: Data type

04-c Language data types