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C Language notes

Knowledge points of array ！

1. One dimensional array creation and initialization

Array ： A collection of elements of the same type ！

1. stay VS2019 It's going to report an error ！2. Some of them DEV++ Inside can ！

The reason is C99 Caused by grammar ！

Array creation （ Initialization and full initialization ）

 

 

 

References to arrays ！ The previous article introduced an operator 【】, This operator is actually an array access subscript operator

To sum up ：1. The use of arrays is accessed by subscripts , Note that the subscript is from 0 At the beginning 2. The size of the array can be calculated ！

 

Two dimensional array ！！

Represents a two-dimensional array of three rows and four columns ！

 

The second is the initialization of the array ： Assign values when creating ！

Int char [3][4]={1,2,3,4,5,6,7,8,9,10};   there 【3】 It can't be zero ！, It will be explained later !

 

Remember a little , Incomplete initialization will be assigned to zero ！

2. Second, arrays are also accessed through subscripts ！

 

For example ：

Mention a sentence ！ Two dimensional arrays are stored continuously in memory ！

A row is internally continuous , Inter bank is also continuous !

 

Say operators

Operators also have categories ：

1. Arithmetic operators ！
2. The displacement operator
3. 
4. <<  >> Shift left operator ： Left discard , Zero on the right The same is true of right movement ！！ Mention the binary representation of integers ： Yes 3 Kind of ,
5. Original code ： The binary sequence written directly according to the value is the original code
6. Inverse code ： The symbol of the original code remains unchanged , The negation of other bits is the inverse code .
7. Complement code ： Inverse code +1, It's complement .
8. Bit operators ：& | ^
9. Assignment operator  &a

 

Pointer elementary

The pointer ：· Pointer number Point to - Address -（ It is also called pointer ）

 

A pointer is a variable used to store addresses （ The values stored in the pointer are treated as addresses ）

The pointer is used to store the address , An address is a unique identifier of an address space ！

An interesting knowledge point ：（ The size of the pointer is 32 Bit platform is 4 Bytes , stay 64 Bit platform is 8 Give byte ） This as a （ Just know ！）

  The meaning of pointer type ：

1. The type of pointer determines ： How much permission does the pointer dereference have ！
2. The type of pointer determines , The pointer takes one step , How far can I go （ step ）

There is a pointer problem that needs to be mentioned ： Many people refer to this as a wild pointer , It means uninitialized ,

 

 

 

there P It's a wild pointer ！（ Also known as crossing the line ）

Avoid the wrong use of pointers ：

1 Initialization of the pointer .

1. Watch out for the pointer .
2. Check the valid value before using the pointer .

The operation of the pointer ：

1. The pointer +- Integers
2. 

 

1. The pointer - The pointer
2. 

 

This section mentions debugging skills

The basic steps of debugging ：

1. Find the existence of program errors
2. To isolate , Eliminate and so on
3. Determine the cause of the error
4. Propose a solution
5. Correct procedural errors , To test

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