c - copy one string in to other using pointer produce Garbage values why? -

if take array fine used *str1 , str2 not work

#include <stdio.h>   void copystr(char* ,char*);  int main()  {      char *str1="xxx";     char *str2= "yyy";      copystr(str1, str2);      printf("\n %s",str2);   }  void copystr(char *dest,char *src)   {       while(*src!='\0')           *dest++=*src++;       *dest='\0';       return;   }  

char *str = "some string" 

here str pointer pointing constant memory, can't edited , leads undefined behaviour.

but if declare like

char str2[] = "some string" 

now str2 above pointing memory not constant , can changed. work.

more explanation here: char *array , char array[]