Selection sort in C programming

In this tutorial, you will learn the concept of selection sort in c programming used for sorting arrays.

Selection sort in C

The selection sort algorithm compares two successive elements of an array repeatedly and swapping if necessary. This is the simple sorting algorithm used in C programming.

If the user wants to sort an array in ascending order then the comparison is made between two elements and the smaller element is placed at the first place. The process is repeated until last elements are compared. Hence, if there are n elements in the array, the total number of comparison are n-1.

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C program to sort elements of an array using selection sort in c programming

For proper understanding of program you must be familiar with following concepts of C programming

• C programming if else
• C programming arrays
• C programming for loop

/* sorting array using selection sort method */

#include <stdio.h>
#define SIZE 5

int main ()
{
   int data[ SIZE ] = { 3, 12, 7, 10, 5};
   int pass, i, temp;

   printf("Original order of data items:\n");

   //printing data items
   for ( i = 0; i < SIZE; ++i)
   {
      printf("%4d", data[ i ]);
   }

   //selection sort algorithm
   for (pass = 0; pass < SIZE; ++pass)
   {
      for ( i = pass + 1; i < SIZE; ++i)
      {
         if ( data[ pass ] > data[ i ])
         {
            //steps for swapping
            temp = data[ pass ];
            data[ pass ] = data [ i ];
            data[ i ] = temp;
         }
      }
   }
   printf("\n\nData items in ascending order:\n");
   for (i= 0; i < SIZE; ++i)
   {
      printf("%4d", data[ i ]);
   }
   return 0;
}

Output

Explanation
In the above example, we have sorted data elements of an array in ascending order. We have defined macro SIZE which is set to 5. The total number of the pass in the above program for sorting are 4.

If the user wants to sort data items of the array in descending order following change should be made in the condition of if.

if ( data[ pass ] < data[ i ])

Now elements of the arrays are sorted in descending order.