c - Why use const char *prt1 when we can't change the containing of the pointer -

if use example:

   char* strs[2];     strs[1] = "hello";     strs[2] = "world!";     strcat(strs[1],strs[2]); 

then access violation comes (access violation writing location 0x0028cc75).

so why use const char *strs[2]; since strs1[1], strs1[2] cannot changed?

two sources of access violation in case

1. string literals read , writing them undefined behavior

2. in c arrays 0 index based, strs[2] not exist, strs[0] , strs[1].

using const prevents accidentally modifying them, not forbid you.

arrays modifiable though,

#include <stdio.h> #include <string.h>  int main(void)  {     char strs[2][11] = {"hello", "world"};     strcat(strs[0], strs[1]);     return 0;  } 

the above works expected it.

here how correctly dynamic allocation

#include <stdio.h> #include <string.h> #include <stdlib.h>  char * autostrcat(const char *const head, const char *const tail)  {     char  *result;     size_t headlen;     size_t taillen;      if ((head == null) || (tail == null))         return null;      headlen = strlen(head);     taillen = strlen(tail);     result  = malloc(1 + headlen + taillen);     if (result == null)         return null;     memcpy(result, head, headlen);     memcpy(&result[headlen], tail, taillen);      result[headlen + taillen] = '\0';     return result;  }  int main(void)  {     const char *strs[2] = {"hello", "world"};     char *result = autostrcat(strs[0], strs[1]);     if (result != null)         printf("%s\n", result);     free(result);     return 0;  } 

since used strlen() know lengths of strings are, using strcat() unecessarily expensive because again figure out length of first string strlen() does.