C language array and bubble sort

1、 Array

integer array 、 Character array 、 Two dimensional array

1.1 Concept

A set of elements with the same data type

characteristic ：（1） Same data type     （2） Address continuous

As shown in the figure above , The address of the array is continuous

1.2 Definition

Storage type   data type   Variable name ;

int a;// An integer variable is defined

Storage type   data type   Array name [ Number of elements ];

int a[5];// An array is defined , Array has 5 Elements

Storage type ：auto、register、static、extern

data type ： The data type of each element in the array

Data type of array ： data type [ Number of elements ]  int [5]

data type ： Removing the variable name is the data type

Array name ： Address of the first element of the array （ Entire array ）

Number of elements ： It must be a definite number （ integer constants ）

1.3 Initialization of an array

1.3.1 Partial initialization

int a[5] = {1,2,3};

a[0] = 1 ,a[1] = 2, a[2] =3, a[3] = ? ,a[4] = ?  a[5] = ?//error

summary ： When the array is partially initialized , If it's not assigned , The default is 0, So we use this feature to clear the array

1.3.2 All initialization

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

int b[ ] = {1,2,3};// The number of elements of the array is determined by the specific number assigned later

1. If the array is defined inside the function body , Not initialized , Its value is random
2. If the array is defined outside the function , Not initialized , Its value is 0
3. If you use static modification , Not initialized , Its value is 0

1.4 Array access

Array name [ Subscript ];

Be careful ： The subscript of an array is from 0 At the beginning

1.5 Array input 、 Output

1.6 Bubble sort

thought ： Compare from left to right , If the former number is larger than the latter one , Just swap places , Otherwise unchanged

2、 A character array

The essence of character arrays ： It's a string , With ‘\0’ As a Terminator

Storage type   data type Array name [ Number of elements ];

char str[6] = {‘h’,’e’,’l’,’l’,’o’,’\0’}; // At most 5 Elements , Leave a place for ’\0’

char str[6] = “hello”;

char str[6] = {“hello”};

Clear the character array ：char str[6] = {‘\0’};

2.1 String output function

puts( Array name );

function ： Print the string in the array to the terminal , And automatically add and wrap lines

Be careful ： encounter ’\0’ end

2.2 Input function of string

gets（ Array name ）;

function ： Put the string entered by the keyboard into the array , And automatically add ’\0’

Be careful ： No cross-border inspection , So don't type more

2.3 summary

2.3.1 scanf and gets The difference between

gets It ends with carriage return , however scanf By return 、Tab Key and space as terminators

buffer ：

gets： When you finish inputting the string , The buffer will be emptied automatically

scanf： When you finish inputting the string , Spaces will be left in the buffer 、 enter 、Tab key

Be careful ：gets First check whether there is any residual content in the buffer , If there is , Just take it and use it , Otherwise input

      scanf Is a standard input function , You can only get the value by entering at a time

2.3.2 puts and printf The difference between

puts Line breaks will be automatically added , and printf Can't