Const pointer of C language and parameter passing of main function

1. const Decorated pointer
2. main Function arguments

1、const Decorated pointer

const： read-only

       Used to modify variables , Use const Decorated variables can only be read , Cannot be modified

int a;// Storage and re stacking area

const int a;// Store in the stack area

Case study ： Judge const Whether the modified variable is in the constant area

char str[30] = “hello”;// stay The stack area Opens the 30 Bytes of space

str[0] = ‘a’;

char *p = “hello”; p Store in stack area , “hello” Is a string constant , So in the constant area

*p = ‘a’;//error because “hello” Stored in the constant area , Cannot be modified

char str[30] = {0};

str = “hello”; //error  str Is a constant

char *p = NULL;

p = “hello”;

const Decorated pointer ：

int a = 10;

const int *p = &a;//const modification *p,*p Cannot be modified

int *const p = &a;//const Modification is p,p We can't change the direction of

const int *const p = &a;*p and p Can't be modified

summary ：const Who is near , Just decorate who

const leave int near , Modification is *p

const leave * near , Modification is p

2、main Function arguments