Searching a string inside a char array using Divide and Conquer - c++

Question

Let's say that I have a struct array and each element has a name. Like:
struct something{
char name[200];
}a[NMAX];
Given a new string (char array), i need to find the correct index for it using divide and conquer. Like:
char choice[200];
cin>>chioce;
int k=myFunction(choice); // will return the index, 0 otherwise
// of course, could be more parameters
if( k )
cout<<k;
I don't know how to create that searching function (I tried, I know how D&C works but i'm still learning! ).
And no, i don't want to use strings !
This is what i tried:
int myFunction(char *choice, int l,int r) // starting with l==0 && r==n-1
{
int m;
if(strcmp(a[m].name,choice)==0)
return m;
else{
m=(l+r)/2;
return myFunction(choice,l,m-1);
return myFunction(choice,m+1,r);
}
}

Answer 1

This is my solution for your above problem. But i have modified a few things in your code.
#include<iostream>
using namespace std;
#define NMAX 10
struct something{
char *name; //replaced with char pointer so that i can save values the way i have done
}a[NMAX];
int myFunction(char *choice, int l,int r) // starting with l==0 && r==NMAX-1
{
if(l>r) //return if l has become greater than r
return -1;
int m=(l+r)/2;
if(strcmp(a[m].name,choice)==0)
return m+1;
else if(l==r) //returned -1 as the value has not matched and further recursion is of no use
return -1;
else{
int left= myFunction(choice,l,m-1);//replaced return
int right= myFunction(choice,m+1,r);//by saving values returned
if(left!=-1) //so that i can check them,
return left; //otherwise returning from here onlywould never allow second satatement to execute
if(right!=-1)
return right;
else
return -1;
}
}
int main(){
a[0].name="abc";
a[1].name="a";
a[2].name="abcd";
a[3].name="abcf";
a[4].name="abcg";
a[5].name="abch";
a[6].name="abcj";
a[7].name="abck";
a[8].name="abcl";
a[9].name="abcr";
char choice[200];
cin>>choice;
int k=myFunction(choice,0,NMAX-1); // will return the index, 0 otherwise
// of course, could be more parameters
if( k !=-1)
cout<<k;
else
cout<<"Not found";
return 0;
}
Hope it will help.