[embedded C foundation] Part 8: explanation of C language array

1 summary

Basic concept of array : A collection of data of the same type

1.1 Definition of array

Storage type data type Array name [ Element number ];
int a[5];

The number of elements must be constant , Can't be a variable

1.2 Initialization of an array

int a;

 Array initialization method
All initialization :
int a[5] = {1, 2, 3, 4, 5};

Local initialization :
int a[5] = {1, 2, 3};
Be careful ： Others are 0;

Commonly used ：int arr[5] = {0}; // Initialize all elements as 0 Array of , Usually this method is used in clearing 0 Use... For arrays

Default initialization :
int a[] = {1, 2, 3, 4, 5};
int arr[] = {0}; // Less commonly used methods , This is equivalent to setting only 1 Array of elements , And the value of 0

Example ：
int a[5] = {0}; // Yes , Local initialization , So all is 0 了
int a[] = {0}; // Yes , An element , Initialize to 0
int a[5] = {1, 2, 3, 4, 5}; // Yes
a = {1, 2, 3, 4, 5}; // wrong

 Initialization is different from assignment
Initialization refers to the assignment of variable values by the system before the program runs , The assignment is completed after the program starts running , The assignment action belongs to program completion

int a; This is a variable definition without initialization
int a=1; This belongs to system initialization , The system applies for variables first a, And put this unit into the initial value 1
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