Binary Search Help Repost.

Siddesh Kannan · 2012-06-29T16:23:58

[color=#000000][font=verdana, arial, helvetica, sans-serif]I've got the logic right and the algo seems to work fine. Now, that's epic for me But..[/font] [color=#000000][font=verdana, arial, helvetica, sans-serif]I want to add 2 more features to this code:[/font] [color=#000000][font=verdana, arial, helvetica, sans-serif]1) Exit on pressing 'x'. For now I'm using -1 to exit.[/font] [color=#000000][font=verdana, arial, helvetica, sans-serif]2) Print a message "Element not found" when an element not present in the array is searched for. Yeah, I'm not able to figure that out :|[/font] [color=#000000][font=verdana, arial, helvetica, sans-serif]Well, Here goes my code:[/font] [font=verdana, arial, helvetica, sans-serif][color=#000000][/font] #include<iostream> using namespace std; int BinSearch(int data[], int numElements, int searchKey); // Prototype int main() { int data[] = {1, 4, 5, 6, 9, 14, 21, 23, 28, 31, 35, 42, 46, 50, 53, 57, 62, 63, 65, 74, 79, 89, 95}; int numElements = 23; // Size of the Array is 23!!! int searchKey; int found; for(int i = 0; i < numElements; i++) cout << data << ", "; cout << endl; for(;;) { cout << "Enter search key: (-1 to exit) "; // I want to quit when I press 'x'. Please let me know. cin >> searchKey; if(searchKey == -1) { cout << "Exiting\n"; break; } found = BinSearch(data, numElements,searchKey); cout << searchKey << " is in position " << found << endl; } } int BinSearch(int data[], int numElements, int searchKey) { int position, mid; int beg = 0; int end = numElements; // Algorithm Begins. for(int i = beg; i <= end;) { mid = (beg+end)/2; if(data[mid] == searchKey) { return mid; } else if(data[mid] > searchKey) { end = mid - 1; } else if(data[mid] < searchKey) { beg = mid + 1; } } } [font=verdana, arial, helvetica, sans-serif][color=#000000][/font] Thanks, --Sid

For Beginners

Started by Sid_TheBeginner June 29, 2012 05:40 AM

21 comments, last by ????? ?????? 11 years, 10 months ago

rip-off

11,000

June 29, 2012 11:32 AM

Your for loop doesn't make any sense in the context of the algorithm. You're not iterating over the array - you're leapfrogging over portions of it. The key observation is that the value of "i" is irrelevant in the loop body. Unless you just want to do something N times, this is a sign that something is amiss.

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