C Language First speaking: C Foundation

1. #import function: Import the header file;

2. There are two forms of the import header file: <>, ""

<> role: Import system framework

"Role: Import files that others have written."

3. Data type Specifies the type and size of the data;4. Integral type:(1). type int: 4 bytes; (2). Short Type: occupies 2 bytes; (3). Char type: 2 bytes;               (4). Long: 64-bit system occupies 8 bytes; The 32-bit system occupies 4 bytes.

' 0 ' character 0 corresponds to decimal integer 48

0 Digit Zero

' 0 '---' 9 ' corresponds to 48--57

' A '--' Z ' corresponds to 65--90

' A '--' z ' corresponds to 97--122

' a ' + = = ' a '

5. Float Type:

(1) Single-precision floating-point type: float is 4 bytes;

(2) Double-precision floating-point type: Double is 8 bytes.

Constant: Amount not to be changed without external force

Integer constants: 89 88 6 ...;

Floating-point constants: 3.1415926 12.01 ...;

Character-type constants: ' A ' 0 ' B ' ...;

Definition of variable: data type variable name = initial value;

The variable definition must be assigned the initial value;

Naming rules for variable names:

1. Consists of numbers, letters, underscores, and numbers cannot begin;

2. Cannot be duplicate with other keywords;

3. Cannot duplicate the name of other variable names;

4. See the name of the Italian.

6. operators:

Assignment operator: "=", assigns the value to the right of the equal sign to the left variable, the process of assigning the value is the process of copying,

Copies a copy of the value to the right of the equal sign to the variable to the left of the equals sign.

Arithmetic operators: "+", "-", "*", "/", "%", "+ +", "-"

Note : + + or--before, the first self-increment (minus), then use, + + or--after the first use, in the self-increment (minus ).

Compound operator:+=,-=,*=,/=,%=

7. expression: Can be made up of constants, variables, and operators

How to tell if it is an expression: there is no value

Statement: With a semicolon ";" End

8. Format output function printf: The output of the target, is to verify that the results are correct

Conversion character

%d--INT

%HD--Short

%ld--long

%f--floating-point type (float,double)

%c-char

Escape character: \ n Enter, percent output%,\\ output \

C Language First speaking: C Foundation