insertionSort-c

#include<stdio.h>
#include<stdlib.h>
#include<time.h>

void insertionSort(int a[], int n)
{
    int key, j;

    for(int i = 1; i < n; i++)
    {
        key = a[i];
        j = i - 1;

        while(j >= 0 && a[j] > key)
        {
            a[j + 1] = a[j];
            j = j - 1;
        }

        a[j + 1] = key;
    }
}

// function to generate random numbers between 0 - 9999
void generateRandomNumbers(int a[], int n)
{
    for(int i = 0; i < n; i++)
    {
        a[i] = rand() % 10000;
    }
}

int main()
{
    int a[10000];
    clock_t start, end;
    double time_taken;
    double theoretical_time;
    FILE *fp;

    srand((unsigned)time(NULL));

    fp = fopen("i_time.txt", "w");
    if(fp == NULL)
    {
        printf("File cannot be opened\n");
        return 1;
    }

    for(int n = 100; n < 10000; n += 100)
    {
        generateRandomNumbers(a, n);

        start = clock();
        insertionSort(a, n);
        end = clock();

        time_taken = (double)(end - start) / CLOCKS_PER_SEC;
        theoretical_time = (double)(n * n) * 1e-8;

        fprintf(fp, "%d %lf %lf\n", n, time_taken, theoretical_time);
    }

    fclose(fp);

    FILE *gP = popen("gnuplot -persistent", "w");

    if(gP == NULL)
    {
        printf("Gnuplot not found\n");
        return 1;
    }

    fprintf(gP, "set title 'Insertion Sort Time Efficiency'\n");
    fprintf(gP, "set xlabel 'Input Size'\n");
    fprintf(gP, "set ylabel 'Time (seconds)'\n");
    fprintf(gP, "set grid\n");
    fprintf(gP, "set term png\n");
    fprintf(gP, "set output 'I_sort_efficiency_c.png'\n");

    fprintf(gP, "plot 'i_time.txt' using 1:2 with linespoints title 'Actual Time',");
    fprintf(gP, "'i_time.txt' using 1:3 with lines lw 2 title 'Theoretical Time'\n");

    fflush(gP);
    pclose(gP);

    return 0;
}