C programming: Strings, arrays, and pointers.

Maxwell Githinji — Mon, 20 May 2024 20:52:02 +0000

In this read, we are going to explore strings, arrays, and pointers. Additionally, we are going to write a block of C code script to help visualize these concepts.

Strings

Unfortunately, unlike other programming languages like Python, Ruby, JavaScript, etc. C does not offer a direct approach to initializing a string. This would ideally mean that it does not have a data type string, instead, it has a data type character. This means that a string in C is mostly initialized as an array of characters or directly using pointers. To initialize a strings, you can follow the below guide or example:

// using Array to initialize an Array

char students[ ] = { "Max", "Brian", "Steve" };

// using Array to initialize a pointer

char *students = { "Max", "Brian", "Steve" };

Arrays

In C, an array can simply be defined as a set of elements of the same data type. Examples of how to initialize a C array can be done as follows:

data_type array_name [size] = {value1, value2, value3, ...};

// example, let's initialize an array with the name num and it holds 10 numbers

int num[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};

// example, let's initialize the same array named num but without determining the array size.

int num[10] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10};


// example, let's initialize an array with float data types

float temperatures[5] = {98.6, 99.5, 100.2, 97.8, 101.3};


// example, let's initialize an array of characters.

char name[3] = "Max";

char nameTwo = "Brian";

// example, let's initialize an array with the name students and it holds names of students as 2D array of characters.

char students[3][10] = {"Brian", "Max", "Steve"};

To access elements in an array is important as it allows you to decide what you want to do with the data stored in these arrays - this may range from displaying the data to mutating the data or the array as a whole. For this article, we will not delve into using loops to access values or data used in arrays, instead, the example below will offer a basic example that shows how to access an array.

#include <stdio.h>

int main() {
    // Declare an array of integers with 5 elements
    int myArray[5] = {10, 20, 30, 40, 50};

    // Access and print elements of the array
    printf("Element 0: %d\n", myArray[0]); // Output: Element 0: 10
    printf("Element 1: %d\n", myArray[1]); // Output: Element 1: 20
    printf("Element 2: %d\n", myArray[2]); // Output: Element 2: 30
    printf("Element 3: %d\n", myArray[3]); // Output: Element 3: 40
    printf("Element 4: %d\n", myArray[4]); // Output: Element 4: 50

    return 0;
}

Pointers

In C, pointers are used to store other variables. These variables can have different data types ranging from integers to floats to char ( characters ). Apart from variables, pointer can also hold arrays, function, and other pointer as well.
To initialize poiters to store various data variables as well as an array, you can follow the examples below:

void intPointers(void) {
    // Initialize an integer, float, and char variable

    int num = 10;

    float myFloat = 10.1;

    char character = "A";

    char name[] = "Max";

    int arr[3] = {1, 2, 3};

    // Initialize pointers to store the addresses of the variables

    int *numPointer = &num;         // Pointer to an integer

    float *myFloatPointer = &myFloat; // Pointer to a float

    char *myCharacterPointer = character;     // Pointer to a character

    char *myNamePointer = name;     // Pointer to a char array (string)

    char *myArrayPointer = arr; // Pointer to an int array

    // Initialize an array of strings as a pointer directly

    char *students = { "Max", "Brian", "Steve" };
}

If you would like to initialize a pointer that holds to call to an already initialized function, you can follow the example below:

void helloWord(void) {
   printf("Hello world");
}

int main(void) {

   void (*func_ptr)() = helloWorld; // Pointer to a function

   func_ptr();  // Calling the function through the pointer

   return 0;
}

Lastly, to store another pointer within another pointer, you can approach it as follows:

void intPointers(void) {
    // Initialize an integer, float, and char variable

    int num = 10;


    // Initialize pointer for the variable num

    int *numPointer = &num;         // Pointer to an integer

    // Initialize pointer for the pointer

    int *pointerForMyPointer = &numPointer;
}

Bubble Sort Algorithm

Maxwell Githinji — Mon, 20 May 2024 20:39:25 +0000

Sorting algorithms are important as they help the programmer to arrange or re-arrange elements depending on their desired format. There are a number of sorting algorithms, among them are:

Bubble sort.
Selection sort.
Insertion sort.
Merge sort.
Quick sort.
Heap sort

In this article, we are going to discuss the bubble sort algorithm. First, let's define and understand how a bubble sort algorithm works. Bubble sort algorithm just like other sorting algorithms, it's mainly concerned with organizing or re-organizing elements. Bubble sort does this by using the ideology of comparison. This would mean that its a step by step approach- for instance, to organize an array with elements "a", "b", and "c", the algorithm would compare element "a" to element "b" and depending on the programmer's desired or defined format, a swap might happen.
Below are examples of code scripts for python, javascript, and C showing how to produce the algorithm.

Bubble sort-algorithm using Python.

def bubble_sort(arr):
    n = len(arr)
    # Traverse through all array elements
    for i in range(n):
        # Track if any elements were swapped in this iteration
        swapped = False
        # Last i elements are already in place, so inner loop can avoid checking them
        for j in range(0, n-i-1):
            # Traverse the array from 0 to n-i-1
            # Swap if the element found is greater than the next element
            if arr[j] > arr[j+1]:
                arr[j], arr[j+1] = arr[j+1], arr[j]
                swapped = True
        # If no elements were swapped in the inner loop, then the array is already sorted
        if not swapped:
            break

Bubble sort-algorithm using JavaScript.

function bubbleSort(arr) {
    let n = arr.length;
    let swapped;

    // Outer loop to iterate over the entire array
    for (let i = 0; i < n; i++) {
        swapped = false;

        // Inner loop to compare adjacent elements
        for (let j = 0; j < n - i - 1; j++) {
            // Swap if the element found is greater than the next element
            if (arr[j] > arr[j + 1]) {
                let temp = arr[j];
                arr[j] = arr[j + 1];
                arr[j + 1] = temp;
                swapped = true;
            }
        }

        // If no elements were swapped, break out of the loop
        if (!swapped) {
            break;
        }
    }
}

Bubble sort-algorithm using C.

#include <stdio.h>

// Function to implement bubble sort
void bubbleSort(int arr[], int n) {
    int i, j, temp;
    int swapped;

    // Outer loop to iterate over the entire array
    for (i = 0; i < n-1; i++) {
        swapped = 0;

        // Inner loop to compare adjacent elements
        for (j = 0; j < n-i-1; j++) {
            // Swap if the element found is greater than the next element
            if (arr[j] > arr[j+1]) {
                temp = arr[j];
                arr[j] = arr[j+1];
                arr[j+1] = temp;
                swapped = 1;
            }
        }

        // If no elements were swapped, break out of the loop
        if (swapped == 0)
            break;
    }
}

// Function to print an array
void printArray(int arr[], int size) {
    int i;
    for (i = 0; i < size; i++) {
        printf("%d ", arr[i]);
    }
    printf("\n");
}

// Main function to test the bubble sort algorithm
int main() {
    int arr[] = {64, 34, 25, 12, 22, 11, 90};
    int n = sizeof(arr)/sizeof(arr[0]);

    printf("Unsorted array: \n");
    printArray(arr, n);

    bubbleSort(arr, n);

    printf("Sorted array: \n");
    printArray(arr, n);

    return 0;
}

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C programming: Strings, arrays, and pointers.

Bubble Sort Algorithm