Basic data types and variables in C

Data types in the C language

1. Basic data types

1) integral type (int%d)

2) character type (char%c)

3) Float type%d

①. Single-precision float (float)

②. Double-precision floating-point type (double)

1. 2. Pointer type void *

   3. Empty type void

2. 4. Construction type

1) Array a[]

2) Structure struct

3) enum enum

4) Common Body Union

Note: There is no Boolean type in the C language, which means that start and pause are generally represented by 0 and 1.

Variables in the C language

(i) Definition

If the value of a data is indeterminate or often needs to be changed, it is represented by a variable.

(ii) Defining variables

Purpose: Variables must be defined before they can be used. Allocate a piece of storage space in memory to the variable to store the data later. If more than one variable is defined, multiple variables are allocated different storage spaces.

Format: Variable type + variable name;

Example: int A;char c;

Note: variable names are identifiers and require a naming convention that conforms to identifiers.

Question: Why are there many types of variables defined?

A: Different types of variables occupy a different size of storage space, because memory is extremely limited, allocating the appropriate storage space can be stored in the least space to save space.

Remember: You should define variables to save as long as you are unsure of the data. Under the 64-bit compiler, the int type occupies 4 bytes, and the total 4x8=32bit,char type is 1 bytes.

(iii) Use of variables

Initialization: There are two kinds of forms. 1.int A;a=10;2.int a=10;

Modify: You can modify the value of a variable and assign it multiple times to overwrite it.

Output: Use placeholder output variables. The various types of placeholders are as follows:

Int%d or%i

Float/double%f (output 6 bits By default, can be controlled using. 2f)

Long%ld

Long Long%lld

Char%c

String%s

Unsigned Long%zd

Basic data types and variables in C