Searching Algorithms in C

Searching is a fundamental concept in computer science. It’s the process of finding a specific item in a collection of items. In C programming, we often need to search for data in arrays or other data structures. This tutorial will guide you through the most popular searching algorithms in C: Linear Search and Binary Search.

Introduction to Searching Algorithms

Searching algorithms are methods used to find a particular item in a data structure. In C, these algorithms are commonly used to search for an element in an array. The two most popular searching algorithms are Linear Search and Binary Search.

Linear Search is a straightforward method for searching. It works by comparing each element in the array with the element we’re searching for. If a match is found, the search ends. Linear Search is best used for unsorted or unordered lists with fewer elements due to its simplicity.

Features of Linear Search Algorithm

  • It is used for unsorted and unordered small list of elements.
  • It has a very simple implementation.

Implementing Linear Search in C

Here’s an example of how to implement a Linear Search in C:

#include <stdio.h>

int linearSearch(int array[], int size, int element) {
    for (int i = 0; i < size; i++) {
        if (array[i] == element) {
            return i;
        }
    }
    return -1;
}

int main() {
    int array[] = {20, 35, 85, 90, 145, 170, 175};
    int element = 90;
    int size = sizeof(array) / sizeof(array[0]);
    int result = linearSearch(array, size, element);
    printf("Element found at index: %d", result);
    return 0;
}
C

In this code, we define a function linearSearch that takes an array, its size, and the element we’re searching for as arguments. It then iterates over the array, comparing each element to the search element. If a match is found, it returns the index of the match. If no match is found, it returns -1.

Binary Search is a bit more complex than Linear Search. It works by repeatedly dividing the search interval in half. The initial interval includes the entire array. If the value of the search key is less than the item in the middle of the interval, the interval is reduced to the lower half. Otherwise, it is reduced to the upper half. The search process repeats on the new interval.

  • It is great to search through large sorted arrays.
  • It has a simple implementation.

Implementing Binary Search in C

Here’s an example of how to implement a Binary Search in C:

#include <stdio.h>

int binarySearch(int array[], int low, int high, int element) {
    if (high >= low) {
        int mid = low + (high - low) / 2;
        if (array[mid] == element)
            return mid;
        if (array[mid] > element)
            return binarySearch(array, low, mid - 1, element);
        return binarySearch(array, mid + 1, high, element);
    }
    return -1;
}

int main() {
    int array[] = {2, 3, 4, 10, 40};
    int element = 10;
    int size = sizeof(array) / sizeof(array[0]);
    int result = binarySearch(array, 0, size - 1, element);
    printf("Element found at index: %d", result);
    return 0;
}
C

Wrapping Up

Searching algorithms are essential in C programming. Understanding how they work and when to use them can significantly improve your coding efficiency. Remember, Linear Search is best for small, unordered lists, while Binary Search is ideal for large, sorted arrays.

Frequently Asked Questions (FAQ)

  1. What is a searching algorithm in C?

    A searching algorithm in C is a method used to find a particular item in a data structure, such as an array. The most common searching algorithms in C are Linear Search and Binary Search.

  2. What are the 3 search algorithms?

    The three most common search algorithms are Linear Search, Binary Search, and Hashing. Linear Search checks each element in the data structure until it finds a match. Binary Search repeatedly divides the search interval in half until it finds the target. Hashing uses a hash function to compute an index into an array of buckets or slots, from which the desired value can be found.

  3. Which searching technique is best in C?

    The “best” searching technique in C depends on the specific circumstances. For small, unsorted data sets, a Linear Search is simple and effective. For larger, sorted data sets, a Binary Search is more efficient. Hashing can be extremely efficient for large data sets, but it requires a good hash function and management of potential collisions.

  4. How to search in C programming?

    In C programming, you can search for an item using a variety of methods. The simplest is a Linear Search, where you start at the beginning of the array and compare each element to the target until you find a match or reach the end of the array. A more efficient method for large, sorted arrays is a Binary Search, where you start in the middle of the array and eliminate half of the remaining elements with each comparison. Another method is Hashing, where you use a hash function to compute an index into an array of buckets or slots, from which the desired value can be found.

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Dr. Mehedi Hasan is a seasoned semiconductor professional, academic and web-designer with over a decade of experience in digital system design and verification as well as web development. Currently a Senior Engineer at AMD in Markham, Ontario, he plays a key role in the development and verification of cutting-edge chip technologies, earning multiple Spotlight Awards for his contributions.

Dr. Hasan holds a Ph.D. in Electrical and Computer Engineering from the University of Saskatchewan and has served in both academia and industry across Canada, Bangladesh, Malaysia, and Saudi Arabia. His expertise spans web-development, UVM-based SystemVerilog verification, static timing analysis (STA), RTL design, and scripting in multiple languages including Python, TCL, Shell as well as web-development tools including HTML, CSS, Javascript.

Passionate about knowledge sharing and education, Dr. Hasan has also worked as an Assistant Professor in Ontario, Canada (at Lakehead University) and Bangladesh University. He is committed to building accessible learning environments and is the founder of SkillSeminary, a platform focused on simplifying complex tech concepts for learners worldwide.

When he's not immersed in chip verification or educational projects, Dr. Hasan enjoys mentoring, researching system development, and promoting open tech education.

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