Insertion Sort Program in C

June 5, 2021

Insertion sort algorithm picks elements one by one and places it to the right position where it belongs in the sorted list of elements. In the following C program we have implemented the same logic.

Before going through the program, lets see the steps of insertion sort with the help of an example.
Input elements: 89  17  8  12  0
Step 1: 89  17  8  12  0 (the bold elements are sorted list and non-bold unsorted list)
Step 2: 17  89  8  12  0 (each element will be removed from unsorted list and placed at the right position in the sorted list)
Step 3: 8  17  89  12  0
Step 4: 8  12  17  89  0
Step 5: 0  8  12  17  89

C Program – Insertion Sort implementation

#include<stdio.h>
int main(){

   /* Here i & j for loop counters, temp for swapping,
    * count for total number of elements, number[] to
    * store the input numbers in array. You can increase
    * or decrease the size of number array as per requirement
    */
   int i, j, count, temp, number[25];

   printf("How many numbers u are going to enter?: ");
   scanf("%d",&count);

   printf("Enter %d elements: ", count);
   // This loop would store the input numbers in array
   for(i=0;i<count;i++)
      scanf("%d",&number[i]);

   // Implementation of insertion sort algorithm
   for(i=1;i<count;i++){
      temp=number[i];
      j=i-1;
      while((temp<number[j])&&(j>=0)){
         number[j+1]=number[j];
         j=j-1;
      }
      number[j+1]=temp;
   }

   printf("Order of Sorted elements: ");
   for(i=0;i<count;i++)
      printf(" %d",number[i]);

   return 0;
}

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