Sequential, binary search (iterative and recursive way)

#include<stdio.h>

int seq_search(int [], int, int);
int bin_search(int [], int, int);
int rbin_search(int [],int, int, int);

void main()
{
//  int arr[]={5,100};
//  int arr[]={5};
//  int arr[]={5,7,9,30,31,39};
//  int arr[]={2,2,5,5,5,5,7,7,7,9,9,9,9,9};
//  int arr[]={100};
//  int arr[]={};
    int arr[]={-5,-3,0,5,39};
    int i,key,size;

    size=sizeof(arr)/sizeof(int);
//  printf("%d",size);

//sequential search

    printf("Using Sequential Search: ");

    if((i=(seq_search(arr,key=5,size)))!=-1)
    {
        printf("\nFound %d at position %d", key, i);
    }
    else
    {
        printf("\n%d was not found",key);
    }

        if((i=(seq_search(arr,key=-3,size)))!=-1)
        {
                printf("\nFound %d at position %d", key, i);
        }
        else
        {
                printf("\n%d was not found",key);
        }

        if((i=(seq_search(arr,key=39,size)))!=-1)
        {
                printf("\nFound %d at position %d", key, i);
        }
        else
        {
                printf("\n%d was not found",key);
        }

     if((i=(seq_search(arr,key=100,size)))!=-1)
        {
                printf("\nFound %d at position %d", key, i);
        }
        else
        {
                printf("\n%d was not found",key);
        }

//Non recursive binary search

    printf("\n\n\nUsing Binary Search(Non-recursive): ");

    if((i=(bin_search(arr,key=5,size)))!=-1)
    {
        printf("\nFound %d at position %d", key, i);
    }
    else
    {
        printf("\n%d was not found",key);
    }

        if((i=(bin_search(arr,key=-3,size)))!=-1)
        {
                printf("\nFound %d at position %d", key, i);
        }
        else
        {
                printf("\n%d was not found",key);
        }

        if((i=(bin_search(arr,key=39,size)))!=-1)
        {
                printf("\nFound %d at position %d", key, i);
        }
        else
        {
                printf("\n%d was not found",key);
        }

     if((i=(bin_search(arr,key=100,size)))!=-1)
        {
                printf("\nFound %d at position %d", key, i);
        }
        else
        {
                printf("\n%d was not found",key);
        }

//recursive binary search

    printf("\n\n\nUsing Binary Search(recursive): ");

    if((i=(rbin_search(arr,key=5,0,size-1)))!=-1)
    {
        printf("\nFound %d at position %d", key, i);
    }
    else
    {
        printf("\n%d was not found",key);
    }

        if((i=(rbin_search(arr,key=-3,0,size-1)))!=-1)
        {
                printf("\nFound %d at position %d", key, i);
        }
        else
        {
                printf("\n%d was not found",key);
        }

        if((i=(rbin_search(arr,key=39,0,size-1)))!=-1)
        {
                printf("\nFound %d at position %d", key, i);
        }
        else
        {
                printf("\n%d was not found",key);
        }

     if((i=(rbin_search(arr,key=100,0,size-1)))!=-1)
        {
                printf("\nFound %d at position %d", key, i);
        }
        else
        {
                printf("\n%d was not found",key);
        }

    printf("\n");
}

int seq_search(int arr[], int key, int size)
{
    int i;

    for(i=0;i<size;i++)
    {
        if(arr[i]==key)
        {
            return i;
        }
    }
    return -1; //not found
}

int bin_search(int arr[], int key, int size)
{
    int low=0, high=size-1,mid;

    while(high>=low)
    {
        mid=(high+low)/2;

        if(arr[mid]==key)
        {
            return mid;
        }
        else if(key<arr[mid])
        {
            high=mid-1;
        }
        else
        {
            low=mid+1;
        }
    }
    return -1; //not found
}

int rbin_search(int arr[], int key, int low, int high)
{
    int mid;

    if(high<low)
    {
        return -1; //not found
    }

    mid=(high+low)/2;

    if(arr[mid]==key)
    {
        return mid;
    }
    else if(key<arr[mid])
    {
        return (rbin_search(arr, key, low, mid-1));
    }
    else
    {
        return (rbin_search(arr, key, mid+1, high));
    }
}