The difference between string pointer and character array

View Code  
  #include<iostream.h>  
 #include<ctype.h>  
    
   /******************************************************************************/  
  /* 
   *    Convert a string to lower case 
   */  
    
  int strlower(char *string)  
 {  
     if(string==NULL)  
     {  
         return -1;  
     }  
   
     while(*string)  
     {  
         if(isupper(*string))  
             *string=tolower(*string);  
         string++;  
     }  
     *string=&#39;\0&#39;;  
     return 0;  
 }  
 /*char *strlower(char *string) 
 { 
     char    *s; 
  
      
  
     if (string == NULL) { 
         return NULL; 
     } 
  
     s = string; 
     while (*s) { 
         if (isupper(*s)) { 
             *s = (char) tolower(*s); 
         } 
         s++; 
     } 
     *s = &#39;\0&#39;; 
     return string; 
 } 
 */  
   
 void main()  
 {  
     char *test="ABCDEFGhijklmN";  
     strlower(test);  
     cout<<test<<endl;  
 }