C Program for Quick Sorting - Quick Sort Program in to Sort Numbers

Quick sort is one of the most efficient sorting algorithms. Here i post a C program to implement Quick sorting. This program is to sort given numbers is ascending order. To sort in descending order using quick sort, only slight changes are needed in program. Changes needed for sorting in descending order are marked in the program as comments.

#include<stdio.h>
void quicksort(int [10],int,int);
int main()
  {
  int x[20],size,i;
  printf("Enter size of the array: ");
  scanf("%d",&size);
  printf("Enter %d elements: ",size);
  for(i=0;i<size;i++)
     scanf("%d",&x[i]);
  quicksort(x,0,size-1);
  printf("Sorted elements: ");
  for(i=0;i<size;i++)
     printf(" %d",x[i]);
  return 0;
  }

void quicksort(int x[10],int first,int last)
  {
  int pivot,j,temp,i;
  if(first<last)
     {
     pivot=first;
     i=first;
     j=last;
     while(i<j)
        {
        while(x[i]<=x[pivot]&&i<last)//for descending, use >= instead of <=
            i++;
        while(x[j]>x[pivot])//for descending, use < instead of >=
            j--;
        if(i<j)
            {
            temp=x[i];
            x[i]=x[j];
            x[j]=temp;
            }
        }
    temp=x[pivot];
    x[pivot]=x[j];
    x[j]=temp;
    quicksort(x,first,j-1);
    quicksort(x,j+1,last);
}
}

Output:
Enter size of the array: 5

Enter 5 elements:
3
8
0
1
2
Sorted elements: 0 1 2 3 8

C Program to Simulate Round Robin CPU Sceduling Algorithm

The round robin CPU scheduling algorithm is simulated using C program. The time slice or time quantum is read from the user.

Program:

#include<stdio.h>
struct process{



int burst,wait,comp,f;
}p[20]={0,0};
int main(){
int
n,i,j,totalwait=0,totalturn=0,quantum,flag=1,
time=0;
printf("\nEnter The No Of Process
:");
scanf("%d",&n);
printf("\nEnter The Quantum time (in ms)
:");
scanf("%d",&quantum);
for(i=0;i<n;i++){
printf("Enter The Burst Time (in ms) For
Process #%2d :",i+1);
scanf("%d",&p[i].burst);
p[i].f=1;
}
printf("\nOrder Of Execution \n");
printf("\nProcess \tStarting\tEnding\tRemaining");
printf("\n\tTime \tTime\tTime");
while(flag==1){
flag=0;
for(i=0;i<n;i++){
if(p[i].f==1){
flag=1;
j=quantum;
if((p[i].burst-p[i].comp)>quantum){
p[i].comp+=quantum;
}
else{
p[i].wait=time-p[i].comp;
j=p[i].burst-p[i].comp;
p[i].comp=p[i].burst;
p[i].f=0;
}
printf("\nprocess # %-3d %-10d %-10d %-10d",i+1,time,time+j,p[i].burst-
p[i].comp);
time+=j;
}}}
printf("\n\n------------------");
printf("\nProcess \t Waiting Time  TurnAround Time ");
for(i=0;i<n;i++){
printf("\nProcess # %-12d%-15d%-15d",i+1,p[i].wait,p[i].wait+p[i].burst);
totalwait=totalwait+p[i].wait;
totalturn=totalturn+p[i].wait+p[i].burst;
}
printf("\n\nAverage\n------------------");
printf("\nWaiting Time : %f ms",totalwait/(float)n);
printf("\nTurnAround Time : %f ms\n\n",totalturn/(float)n);
return 0;
}

C Program to Simulate the ls Command in Linux Operating system

This is a c program to do Simulation of ls Command in linux. The ls command lists all the contents of the directory including filse and sub-directories. The following c program in simulates the ls command.

#include<stdio.h>
#include<dirent.h>
main()
{
char dirname[10];
DIR*p;
struct dirent *d;
printf("Enter directory name\n");
scanf("%s",dirname);
p=opendir(dirname);
if(p==NULL)
  {
  perror("Cannot find directory");
  exit(-1);
  }
while(d=readdir(p))
  printf("%s\n",d->d_name);
}

Related Posts:

C Program to Simulate ls Command in Linux
C Program to Simulate Round Robin CPU Scheduling Algorithm
C Program to Simulate Priority CPU Scheduling Algorithm
C Program to Simulate First Come First Serve (FCFS) CPU Scheduling Algorithm
C Program to Simulate rmdir Command or Delete Directory
C Program to Open, Read and Write Files
C Program to Create Process and Display Process ID - OS Lab Program
How to Use Fork and Exec System Calls
How to Use Exit System Call
C Program to make Parent Process Wait for Child to Terminate
C Program to Simulate GREP Command in Linux
C Program to make Child Process an Orphan Process
C Program to Show Process ID in Linux
C Program for Inter Process Communication using Pipes or Named Pipes (Chat Program)
C Program to Create a Process Using Fork System Call

C Program to Simulate grep Command in Linux

This post contains C program to simulate grep command in Linux or Unix operating systems

Simulation of  grep command in Linux

#include<stdio.h>
#include<string.h>
void main()
{
char fn[10],pat[10],temp[200];
FILE *fp;
printf("Enter file name\n");
scanf("%s",fn);
printf("Enter pattern to be searched\n");
scanf("%s",pat);
fp=fopen(fn,"r");
while(!feof(fp))
{
fgets(temp,1000,fp);
if(strstr(temp,pat))
  printf("%s",temp);
}
fclose(fp);
}

Related Posts:

C Program to Simulate ls Command in Linux
C Program to Simulate Round Robin CPU Scheduling Algorithm
C Program to Simulate Priority CPU Scheduling Algorithm
C Program to Simulate Shortest Job First (SJF) CPU Scheduling Algorithm
C Program to Simulate First Come First Serve (FCFS) CPU Scheduling Algorithm
C Program to Simulate rmdir Command or Delete Directory
C Program to Open, Read and Write Files
C Program to Create Process and Display Process ID - OS Lab Program
How to Use Fork and Exec System Calls
How to Use Exit System Call
C Program to make Parent Process Wait for Child to Terminate
C Program to make Child Process an Orphan Process
C Program to Show Process ID in Linux
C Program for Inter Process Communication using Pipes or Named Pipes (Chat Program)
C Program to Create a Process Using Fork System Call

C Program to Remove (Delete) a Directory using LINUX System Calls

This is a C program to delete  or remove a directory using the system calls in Linux or Unix operating systems. The program make use of the remove() system call in Linux.

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



char fn[10];
printf("Enter source filename\n");
scanf("%s",fn);
if(remove(fn)==0)
printf("File removed\n");
else
printf("File cannot be removed\n");
}

C Program to open, read and write files and perform file copy operation usingSystem Calls in UNIX

Write a program to open, read and write files and perform file copy operation. This program show how to open, read, write and copy files using Linux or Unix system calls like open(), read() and write().

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


char buff[1000],fn1[10],fn2[10];
int fd1,fd2,n;
printf("Enter source filename\n");
scanf("%s",fn1);
printf("Enter destination file name\n");
scanf("%s",fn2);
fd1=open(fn1,O_RDONLY);
n=read(fd1,buff,1000);
fd2=open(fn2,O_CREAT|O_WRONLY);
n=write(fd2,buff,n);
close(fd1);
close(fd2);
}

C Program to Open, Read and Write a file using System Calls

This is a C program to open , read and write files using system calls in Linux (UNIX) operating systems. The system calls open(), read() and write() are used in the C program to open, read and write files in Unix/Linux operating systems.

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


char buff[100],fn[10];
int fd,n;
printf("Enter file name\n");
scanf("%s",fn);
fd=open(fn,O_RDONLY);
n=read(fd,buff,100);
n=write(1,buff,n);
close(fd);
}

Using System calls in C Program to rename a Directory in Linux

C Program to rename a directory in Unix or Linux operating systems using system call rename().

#include<stdio.h>
main()
{

char s[10],d[10];
printf("Enter source Dir Name:\n");
scanf("%s",s);
printf("Enter New Dir Name:\n");
scanf("%s",d);
if(rename(s,d)==-1)
perror("Can't be changed\n");
else
printf("%s is changed to %s\n\n",s,d);
}

How to Create process and display Process ID (pid) of Both Parent and Child

This program shows how to create process and display Process ID (pid) of Both Parent and Child processes. The process is created using the fork system call in UNIX (Linux) operating systems.

#include<stdio.h>
#include<dirent.h>
main(int argc,char **argv)
{

int pid,i;
for(i=0;i<atoi(argv[1]);i++)
{
pid=fork();
if(pid==0)
{
printf("child process id %d Parent process
id %d\n",getpid(),getppid());
}}}

How to use fork and exec System Call

Using fork and exec System calls in Linux (UNIX) operating systems. Fork system call is used to create a child process from a parent process.
#include<stdio.h>
main()
{

int pid;
pid=fork();
printf("%d\n",pid);
if(pid==0)
{
exec("/bin/date\n",NULL,NULL);
exit(0); }
else
{
printf("Parent process %d\n",pid); }}
if(sp)
while(dd=readdir(sp))
printf("--> %s\n",dd->d_name);
}
}

How to use exit() System call

C program to show how to use exit system call. The function exit() is used to exit from a process (or to terminate a process). This works both in Linux or UNIX and Windows operating systems.

#include<stdio.h>
main()
{

int pid;
pid=fork();
printf("%d\n",pid);
if(pid<0)
{
perror("Child can't be executed\n");
exit(-1);
}
else
{
printf("Child created\n");
exit(0);
}
}

C Program To Implement Circular Linked List

C Program to implement circular linked list.

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

struct node
    {
    int info;
    struct node *link;
    }*last;
void create_list(int num);
void addatbeg(int num);
void addafter(int num,int pos);
void del(int num);
void display();
void main()
    {
    int choice,n,m,po,i;
    last=NULL;
    while(1)
        {
        printf("1.Create List\n");
        printf("2.Add at begining\n");
        printf("3.Add after \n");

printf("4.Delete\n");

        printf("5.Display\n");
        printf("6.Quit\n");
        printf("Enter your choice : ");
        scanf("%d",&choice);

switch(choice)
           {
           case 1: printf("How many nodes you want : ");
                   scanf("%d",&n);
                   for(i=0; i < n;i++)
                      {
                      printf("Enter the element : ");
                      scanf("%d",&m);
                      create_list(m);
                      }
                   break;
           case 2: printf("Enter the element : ");
                   scanf("%d",&m);
                   addatbeg(m);
                   break;
           case 3: printf("Enter the element : ");
                   scanf("%d",&m);
                   printf("nter the position after which this element is inserted: ");
                   scanf("%d",&po);
                   addafter(m,po);
                   break;
           case 4: if(last == NULL)
                        {
                        printf("List underflow\n");
                        continue;
                        }
                   printf("Enter the number for deletion : ");
                   scanf("%d",&m);
                   del(m);
         break;
           case 5: display();
     break;
           case 6: exit(0);
           default:printf("Wrong choice\n");
           }
       }
   }
void create_list(int num)
   {
   struct node *temp;
   temp=(node*)malloc(sizeof(struct node));
   temp->info = num;
   if(last == NULL)
       {
       last = temp;
       temp->link = last;
       }
   else
       {
       temp->link = last->link;
       last->link = temp;
       last = temp;
       }
   }

void addatbeg(int num)
    {
    struct node *temp;
    temp =(node*)malloc(sizeof(struct node));
    temp->info = num;
    temp->link = last->link;
    last->link = temp;
    }
void addafter(int num,int pos)
    {
    struct node
    *temp,*q;
    int i;
    q = last->link;
    for(i=0;i<pos-1;i++)
       {
       q = q->link;
       if(q==last->link)
           {
    printf("There are less than %d elements\n",pos);
           return;
    }
       }
    temp =(node*)malloc(sizeof(struct node) );
    temp->link = q->link;
    temp->info = num;
    q->link = temp;
    if(q==last)  //Element inserted at the end
        last=temp;
    }//End of addafter()

void del(int num)
    {
    struct node *temp,*q;
    if( last->link == last && last->info == num)  //Only one element
        {
        temp=last;
        last = NULL;
        free(temp);
        return;
 }
    q = last->link;
    if(q->info == num)
        {
 temp = q;
        last->link = q->link;
        free(temp);
        return;
 }
    while(q->link !=last)
        {
        if(q->link->info==num) //Element deleted in between
           {
           temp = q->link;
           q->link = temp->link;
           free(temp);
           printf("%d deleted\n",num);
           return;
           }
       q = q->link;
       }
   if(q->link->info==num) //Last element deleted q->link=last
       {
       temp = q->link;
       q->link = last->link;
       free(temp);
       last = q;
       return;
       }
   printf("Element %d not found\n",num);
   }

void display()
   {
   struct node *q;
   if(last == NULL)
      {
      printf("List is empty\n");
      return;
      }
   q = last->link;
   printf("List is :\n");
   while(q != last)
      {
      printf("%d ", q->info);
      q = q->link;
      }
   printf("%d\n",last->info);
   }

Program to Display All Armstrong Numbers upto 1000

This post is for C program to display all Armstrong numbers less than 1000. But before all, I should tell what an Armstrong number is. An Armstrong number is a number that is the sum of its own digits each raised to the power of the number of digits. Consider an example. 153 is an Armstrong number. Since it is a 3 digit number, to check whether it is an Armstrong number or not, we should add the 3rd power digits together. So, in the program, we should have a code to determine number of digits in number, then add the n^th powers (where n is the number of digits) of each digit in the number and check whether both the sum and original number are the same.

#include<stdio.h>
#include<math.h>
void main()
{
int n,sum,r,digits;
for(n=1;n<=1000;n++)
  {
  digits=0;
  r=n;
  sum=0;
  while(r!=0)  //Counting Digits
    {
    digits++;
    r/=10;
    }
  r=n;
  while(r!=0)  /*Adding Digits Raised To a Power That Is Equal To Number of Digits *
    {
    sum+=pow((r%10),digits);
    r=r/10;
    }
  if(sum==n)
    {
    printf("%5d",sum);
    }
      }
}

Determinant of Matrix Program - Program to Find Determinant of Matrix

In this post i am sharing a C program to calculate determinant of matrices. Determinant exists only for square matrix. Here i have wrote a c program to find determinant of matrices of order less than or equal to 3.

#include<stdio.h>

void main()
{
int a[10][10],i,m,j;
int det=0;
printf("\nEnter the order of matrix:\n ");
scanf("%i",&m);
printf("\nenter elements\n");
for(i=0;i<m;i++)
 {
 for(j=0;j<m;j++)
  scanf("%d",&a[i][j]);
 }
printf("\nThe matrix is\n");
for(i=0;i<m;i++)
 {
 printf("\n");
 for(j=0;j<m;j++)
  printf("%3d",a[i][j]);
 }
printf("\nthe transpose is\n");
for(i=0;i<m;i++)
{
for(j=0;j<m;j++)
printf("%3i",a[j][i]);
printf("\n");
}
if(m==1)
{
det=a[0][0];
printf("det=%i",det);
}
else if(m==2)
{
int k=1,l=1;
for(i=0;i<2;i++)
for(j=0;j<2;j++)
{
if(i==j)
k*=a[i][j];
else
l*=a[i][j];
}
printf("\ndeterminant=%i",k-l);
}
else if(m==3)
{
for(i=0;i<3;i++)
det=det+(a[0][i]*(a[1][(i+1)%3]*a[2][(i+2)%3]-a[1][(i+2)%3]*a[2][(i+1)%3])); 
printf("\nDeterminant of matrix is: %d",det);
}
else
printf("This program can't calculate determinant of matrix of order greater than 3");
}