C language array

Catalog

One dimensional array ：

One dimensional array creation ：

One dimensional array initialization ：

One dimensional array storage in memory ：

Two dimensional array ：

The creation of two-dimensional array ：

2D array initialization ： 

Array out of bounds ：

Array name ： 

Bubble sort ：

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One dimensional array ：

One dimensional array creation ：

Format ： Element type       Array name   [ Constant expression ]

Such as ：int  arr[10]  ;

const  int n=10;

int arr[n];     // from const    It's a constant variable   In essence, it is a variable , So it doesn't work

notes ： Array creation , stay C99 Before standard , [] I want to give one Constant Can only be , You can't use variables . stay C99 The standard supports the concept of variable length arrays .

One dimensional array initialization ：

int   arr[5]={1,2,3,4}    // The result is ：  1   2  3   4   0      The number of characters is less than [] From inside 0 To mend

int   arr[]={1,2,3,4}        // The result is ：      1   2  3   4   

char   ch[]={'a','b','c'}    // The result is ：     a    b   c

char   ch[]={'a',98,'c'}    // The result is ：     a    b   c          Because in ASCII Characters in the table b Of ASCII The value is 98

char   ch[4]={'a','b','c'}    // The result is ：     a    b   c  \0       

char   ch[]="abc"   // The result is ：     a    b   c   \0

  Arrays are accessed using subscripts , The subscript is from 0 Start .

int  arr[10]={1,2,3,4,5};

printf("%d\n",arr[4]);        

assignment 1~10

#include <stdio.h>
int main()
{
 int arr[10] = {0}; 
 int i = 0;
 for(i=0; i<10; i++)
 {
 arr[i] = i+1;
 } 
 for(i=0; i<10; i++)
 {
 printf("%d ", arr[i]);
 }
 return 0; 
}

The size of the array can also be calculated ：

int arr[10];

int sz = sizeof(arr);// Find the number of bytes

int sz = sizeof(arr1[10]);// Find the byte of an element

int sz = sizeof(arr)/sizeof(arr[0]);// Find the number of elements

One dimensional array storage in memory ：

#include <stdio.h>
int main()
{
 int arr[10] = {0};
 int i = 0;
    int sz = sizeof(arr)/sizeof(arr[0]);
    
 for(i=0; i<sz; ++i)
 {
 printf("&arr[%d] = %p\n", i, &arr[i]);
 }
 return 0;
 }

  As the array subscript grows , Address of element , It's also increasing regularly .

Two dimensional array ：

The creation of two-dimensional array ：

int arr[3][5];           //3 That's ok 5 Column

char arr[3][5];        //3 That's ok 5 Column

double arr[2][4];    //2 That's ok 4 Column

2D array initialization ： 

int arr[3][5]={1,2,3,4,5,6};

 //      { 1  2  3  4  5 }

         { 6  0  0  0  0 }

         { 0  0  0  0  0 }

If you want to put the 1,2 There is the first line ,3,4 There is the second line ,5,6 There is a third line ：

int arr[3][5]={ {1,2},{3,4},{5,6}};

 //      { 1  2  0  0  0 }

         { 3  4  0  0  0 }

         { 5  6  0  0  0 }

When initializing a two-dimensional array Lines can be omitted , Columns cannot be omitted

  Want to print this       

int arr[3][5]={ {1,2},{3,4},{5,6}};

The code is as follows ：

#include <stdio.h>
int main()
{
    int arr[3][5] = { {1,2},{3,4},{5,6} };
    int i = 0;
    for (i = 0; i < 3; i++)
    {
        int j = 0;
        for (j = 0; j < 5; j++)
        {
            printf("%d", arr[i][j]);

        }
        printf("\n");
    }
    return 0;
}

  Two dimensional array storage ：

#include <stdio.h>
int main()
{
 int arr[3][5];
 int i = 0;
 for(i=0; i<3; i++)
 {
 int j = 0;
 for(j=0; j<5; j++)
 {
 printf("&arr[%d][%d] = %p\n", i, j,&arr[i][j]);
 }
 }
 return 0; }

Two dimensional arrays are also stored continuously in memory .

Array out of bounds ：

#include <stdio.h>
int main()
{
 int arr[10] = {1,2,3,4,5,6,7,8,9,10};
    int i = 0;
    for(i=0; i<=10; i++)
   {
        printf("%d\n", arr[i]);// When i be equal to 10 When , Cross border visit 
   }
 return 0;
 }

Array name ： 

The array name is the address of the first element of the array .

There are two exceptions ：

1.sizeof( Array name ), The array name is not the address of the first element of the array , The array name represents the entire array , It calculates the address of the entire array .

2.& Array name , The array name is not the address of the first element of the array , The array name represents the entire array , It takes out the address of the entire array .

#include <stdio.h>
int main()
{
    int arr[10] = {1,2,3,4,5,6,7,8,9,10};

    printf("%p\n", arr);
    printf("%p\n", arr+1);

    printf("%p\n", &arr[0]);
    printf("%p\n", &arr[0]+1);

    printf("%d\n", sizeof(arr));

    printf("%p\n", &arr);
    printf("%p\n", &arr+1);

    return 0;
}

 

  

Bubble sort ：

Array 2 Compare adjacent elements , If the order is not satisfied, exchange .

Such as ： take 3,1,4,2,5,7,6,8,10,9  Sort （ Ascending ）

#include <stdio.h>
//void  bubble_sort(int* arr[], int sz)
void  bubble_sort(int arr[], int sz)
{
	int i = 0;
	for (i = 0; i < 10; i++)
	{
		int j = 0;
		for (j = 0; j < sz - 1 - i; j++)
		{
			if (arr[j] > arr[j + 1])
			{
				int tmp = arr[j];
				arr[j] = arr[j + 1];
				arr[j + 1] = tmp;

			}
		}
	}
}
int main()
{
	int arr[10] = { 3,1,4,2,5,7,6,8,10,9 };
	int sz = sizeof(arr) / sizeof(arr[0]);
	bubble_sort(arr, sz);
	int i = 0;
	for (i = 0; i < sz; i++)
	{
		printf("%d ",arr[i]);
	}
	return 0;
}

 

  If the sequence is correct , It's just an exchange , You can optimize ：

#include <stdio.h>
void  bubble_sort(int arr[], int sz)
{
	int i = 0;
	for (i = 0; i < 10; i++)
	{
		int flag = 1;
		int j = 0;
		for (j = 0; j < sz - 1 - i; j++)
		{
			if (arr[j] > arr[j + 1])
			{
				flag = 0;
				int tmp = arr[j];
				arr[j] = arr[j + 1];
				arr[j + 1] = tmp;

			}
		}
		if (1 == flag)
		{
			break;
		}
	}

}
int main()
{
	int arr[10] = { 3,1,4,2,5,7,6,8,10,9 };
	int sz = sizeof(arr) / sizeof(arr[0]);
	bubble_sort(arr, sz);
	int i = 0;
	for (i = 0; i < sz; i++)
	{
		printf("%d ", arr[i]);
	}
	return 0;
}

The above content is array related .

May all of you encourage it ！！！！