C language summary, C Language

C language summary, C Language

Summary of the 11-day course (only for summary. For details, refer to the previous section)

I. Ordered Structure

Code structure executed from top to bottom

When a computer executes a program, it is compiled into binary files, which are further divided

Binary: for example, 101001001 is a binary number.

Octal: for example, 023767 is an octal digit. The preceding 0 indicates an octal digit.

Decimal: 10, 33, 22 is a decimal number

Hexadecimal: 0x28AD represents a hexadecimal number, and 0x represents a hexadecimal number.

OPERATOR:

Int a = 10, B = 20;

Arithmetic Operators

+: Addition operation example: a + B = 20

-: Subtraction a-B =-10

*: Multiplication a * B = 200

/: Division operation a/B = 0 (integer division results take the integer part, not after the decimal point) any number except 10 is equivalent to removing a single digit

%: Remainder operation a % B = 10

Comparison operator (boolean type)

>: Whether the comparison is greater than a> B false

<: Whether the comparison is less than a <B true

=: Whether the comparison is equal to a = B false

>=: Greater than or equal to a> = B false

<=: Less than or equal to a <= B false

% =: Returns the remainder equal

! =: Not equal

Logical operators (boolean type)

&: And when condition 1 & condition 2 both meet condition 1 and condition 2, the result is true (one is false, two are true)

|: Or condition 1 | condition 2 is true when one condition is met (true or false)

! : Not required! Returns the Boolean value of a condition.

Constants, variables, and expressions

Constant: cannot be changed in the program

Variable: can be changed in the program

Expression: A sub-expression that combines constants, variables, and operators.

Ii. Select Structure

Optional Execution Code

If (conditional expression ){

Statement

}

If (conditional expression 1 ){

Statement 1

} Else if (condition expression 2 ){

Statement 2

}...

Switch (){

Case1 :{

Statement 1;

Break;

}

Case2 :{

Statement 2;

Break;

}

...

Default :{

Statement;

Break;

}

}

Iii. Loop Structure

When a loop condition is met, the structure of a code (loop body) is repeatedly executed.

For Loop

For (Conditional Variable initialization; conditional expression; conditional variable increment ){

Statement (loop body)

}

While Loop

Initial Value of the condition variable;

While (conditional expression ){

Statement (loop body );

Conditional Variable increment;

}

Do... while loop (basically not used)

Do (statement (loop body )){

Conditional Variable Increment

} While (conditional expression)

Iv. arrays and struct

One-bit array, two-dimensional array, multi-dimensional array, character array, String Array

Must be composed of elements of the same data type

Two-dimensional array sorting (Bubble Sorting)

Int arr [5] = {2, 6, 3, 7, 5}; // count is the size of the array.

For (int I = 0; I <count-1; I ++ ){

For (int j = 0; j <count-1-I; j ++ ){

If (arr [j]> arr [j + 1]) {

Int temp = arr [j];

Arr [j] = arr [j + 1];

Arr [j + 1] = temp;

}

}

}

Struct: it can store multiple types of elements.

Struct student {

Struct variable 1;

Struct variable 2;

...

};

When we define a struct, we use typedef to redefine a new name for the struct.

Typedef struct {

Struct variable 1;

Struct variable 2;

...

} Student; // give Student a new name to the struct.

In addition, define (macro definition) and enum (enumeration) are also struct

Struct array: used to store struct Variables

Example:

Typedef struct {

Char name [20];

Int age;

Float score;

} Student;

Student stu1 = {"xiaoming", 20, 80 };

Student stu2 = {"xiaohong", 19, 90 };

Student stu [] = {stu1, stuff };

Printf ("% s % d %. 2f ", stu [1]. name, stu [1]. age, stu [1]. score) // Add (. variable name)

5. Functions (For details, refer to the function article)

Encapsulate code blocks that implement a function

For example, formatted input and output functions

Printf ("") Output Function

Scanf ("", & variable name) Input Function

Such functions provided by the system are called system functions, and the functions compiled by the compiler themselves are called custom functions.

For example:

Int sum (int a, int B ){

Return a + B;

}

This is a user-defined summation function.

Functions are divided:

No parameter no return value: void (){

Printf ("hello ");

}

No parameter has returned value: int B (){

Return 3;

}

There are parameters and no return value: void c (int x ){

Printf ("hui zi ");

}

Parameters return values: int d (int y ){

Return y;

}

Function writing steps:

1: function declaration

2: Writing Functions

3: function call

6. pointer (see the first two articles for details)

A pointer is an address that points to a variable address.

Function pointers and pointer Functions

A function pointer is a pointer pointing to a function.

A pointer function is a function, and the return value is a pointer.

Struct pointer

Pointer to struct

7. dynamic memory Division (see the first two articles for details)

Stack zone: the memory address is the highest, and all declared variables and so on are here. The stack cannot be released automatically after the first release.

Heap zone: The maximum memory space. Manual application and release are required.

Global zone (static zone): stores global variables and adds static variables before any variables. The variables are placed in the global zone.

Constant Area: stores constants.

Code zone: the zone where CPU commands generated by code compilation are stored