Sorting a dynamic 2-dimensional array of Strings

Difficulty Level : Easy
Last Updated : 10 Sep, 2018

Prerequisite: How to dynamically allocate a 2D array in C?

Double pointer: A pointer pointing to another pointer is known as a Double pointer. To represent the double pointer ‘ ** ‘ is used. Double pointer is also called as pointer to pointer.

Example:

Input: Geeks, Gfg,  Placement, Sudo, Gate
Output: Gate, Geeks, Gfg, Placement, Sudo

The idea is to dynamically allocate memory and values to the strings in a form of a 2-D array. Then apply bubble sort using strcmp and strcpy function.

Below is the required implementation:

// C program to sort an array of strings
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
  
// Function to sort the values
void sort(char** names, int n)
{
    int i, j;
  
    // Perform sort operation using bubble sort
    for (i = 0; i < n - 1; i++)
        for (j = 0; j < n - i - 1; j++)
            if (strcmp(names[j], names[j + 1]) > 0) {
                char* temp;
                temp = (char*)calloc(30, sizeof(char));
                strcpy(temp, names[j]);
                strcpy(names[j], names[j + 1]);
                strcpy(names[j + 1], temp);
            }
}
  
// Driver code
int main()
{
    char** names;
    int n, i;
    printf("Enter the number of names to be printed: ");
    scanf("%d\n", &n);
  
    // allocating memory for 1st dimension
    names = (char**)calloc(n, sizeof(char*));
  
    for (i = 0; i < n; i++)
    // allocating memory for 2nd dimension
    {
        names[i] = (char*)calloc(30, sizeof(char));
        scanf("%s", names[i]);
    }
    sort(names, n);
  
    printf("\nArray after sorting:\n");
    for (i = 0; i < n; i++)
        printf("%s\n", names[i]);
  
    return 0;
}

Output:

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Sorting a dynamic 2-dimensional array of Strings