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# How to do an iterative binary search in multiple languages

Tarun Telang

A binary search algorithm searches for a specific item in a sorted collection with specific left and right indices. If the collection is unordered, we need to sort it before applying a binary search. The sorted collectionalso known as the search space is divided into two halves after every comparison. Hence, the algorithm runs with a logarithmic time complexity of $O(log(n))$.

Binary search returns the item’s index location in the collection if the search succeeds; otherwise, it returns the appropriate error messages or values.

## Code

Below is the code used in multiple languagesi.e., JavaScript, Python, and C++ to perform a binary search on an array using iterative implementation:

// function to perform binary search
const binarySearch = (array, target) =>  {
if (array == null || array.length == 0)
return -1;

let left = 0; // left boundary of search space
let right = array.length - 1; // right boundary of search space
while (left <= right) {
// index used in determining whether to search left or right.
let middle = Math.floor((left + right)/2);
if (target === array[middle]){
return middle;
} else if (target < array[middle]) {
right = middle - 1;
} else {
left = middle + 1;
}
}
return -1;
}

// array - collection to be searched.
let array= [2, 4, 5, 6, 7, 8, 23, 34, 54, 56];

// target - value to be searched
let target = 8;

console.log(binarySearch(array, target));
// returns 5, the index of the target in the array.

target = 9; // now searching for 9
console.log(binarySearch(array, target)); // returns -1

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python
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Tarun Telang
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