Summary of array knowledge points

6、 ... and 、 Array

1. To define an array

Format ： Type specifier Array name [ Constant expression ]

• 1.#define N 5 int X[2*N]
• 2.int N=10; int X[N]; //N Can't be a variable
• 3.int X[0…10]; // Illegal expression
• 4.int X[ ]; // Expression cannot be empty

2. Two dimensional array

Format : Type specifier Array name [ Constant expression 1] [ Constant expression 2]

* remarks ： Constant expression 1 Not required . eg： int x[ ] [10]

3. Array processing functions <string.h>

• puts(s1): The string s1( With ’\0’ end ) Output to terminal ;
• gets(s1): Input a string from the terminal to the character array s1 in ;
• strcpy(s1,s2): take s2 Copy the contents of to s1 In your storage space , return s1 The first address ;
• strcat(s1,s2): take s2 Content in connects to s1 At the end of , And back to s1 The first address ;
• strlen(s1): Compute string s1 The length of ( With ’\0’ As an end sign ,’\0’ Do not count the array length ！);
• strcmp(s1,s2): take s1、s2 Two strings from left to right ( Press ASCII Code size ) Compare character by character , Take the size of the first different character as the comparison result .【s1>s2 The return value is positive ;s1=s2 The return value is 0 ; s1<s2 The return value is negative 】

4. Example

void fun(char *t ,char *s)
{
    
	while(*t!=0) t++;        // Formal parameter pointer t The content of is not 0, be t increase 1, Until zero ;
	while((*t++=*s++)!=0)    // take s The indicated content is assigned to t The address referred to , Then add one to both , until t The contents referred to are 0. 【 amount to :strcat()】
}