Given two strings A and B, how would you find out if the characters in B were a subset of the characters in A?

Here is a code in c:

#include <stdio .h>
#include <conio .h>

int isSubset(char *a, char *b);
int main(){

 char str1[]="defabc";
 char str2[]="abcfed";

 if(isSubset(str1, str2)==0)
   printf("\nYes, characters in B=[%s] are a subset of characters in A=[%s]\n",str2,str1);
 }
 else
 {
   printf("\nNo, characters in B=[%s] are not a subset of characters in A=[%s]\n",str2,str1);
 }
 getch();
 return(0);
}

// Function to check if characters in "b" are a subset
// of the characters in "a"
int isSubset(char *a, char *b)
{
 int letterPresent[256];
 int i;
 for(i=0; i<256; i++)
    letterPresent[i]=0;
 
 for(i=0; a[i]!='\0'; i++)
    letterPresent[a[i]]++;
 
 for(i=0; b[i]!='\0'; i++)
    if(!letterPresent[b[i]])
       return(1);
 return(0);
}

same code can be achieved in java by using hashset or array of 256 char as well.