Print a Line with Empty Main()

#include <iostream> using namespace std; class MyClass { public: MyClass() { cout << "Hello!World."; } }m; int main() { }

Quine

Quine

Computing

A quine is a computer program which takes no input and produces a copy of its own source code as its only output.

There are two method doing this

1.Using File Handling

2.Using String

Method 1

#include <stdio.h>

#include <string.h>

main()

{

   FILE *fp;

   char buff[255];

   fp = fopen("input.txt", "r");

   if( fp != NULL ){

      while ( !feof(fp ) ){

         memset(buff, '\0', sizeof( buff) );

         fgets(buff, 255, (FILE*)fp);

         printf("%s", buff );

      }

      fclose(fp);

   }

}

Method 2

#include <iostream>

#include<string>

using namespace std;

int main()

{  string s="#include <iostream>@"

"#include<string>@"

"using namespace std;@"

"int main()@"

"{  string s=;@"

 "for(int i=0;i<s.length();i++)@"

   "if(s[i]=='@')@"

   "cout<<endl;@"

   "else@"

  " cout<<s[i];@"

  " return 0;@"

"}@";

   for(int i=0;i<s.length();i++)

   if(s[i]=='@')

   cout<<endl;

   else

   cout<<s[i];

   return 0;

}

Permutation of a given String.

#include<iostream>
#include<algorithm>
#include<string>
using namespace std;
int main()
{
    string s;
    cin>>s;
    cout<<"\n Permutations Are\n";
    do
    {
        cout<<s<<"\n";
    }while(next_permutation(s.begin(),s.end()));
return 0;
}

Permutation of a Given Values.

Q. Let given values are 1,2,3.
The permutations are
123
132
213
231
312
321

Source Code is:-


#include<iostream>
#include<algorithm>
#include<vector>
using namespace std;
int main()
{
    vector<char> v;
    int n;
    char num;
    cout<<"\n Emter N::";
    cin>>n;
    cout<<"\n Enter Elements:";
    for(int i=0;i<n;i++)
       {
        cin>>num;
        v.push_back(num);
       }
    cout<<"\n Elements Are::";
    for(int i=0;i<v.size();i++)
        cout<<" "<<v[i];
    cout<<"\n Permutations Are\n";
    do
    {
      for(int i=0;i<v.size();i++)
    {   if(i%5==0)
        cout<<"\n";
        cout<<" "<<v[i];
    }
    cout<<"\t";
    }while(next_permutation(v.begin(),v.end()));
    return 0;
}

Compress a String.

Ques. How to compress string in the given format?
Write a function that takes as input a string such as "aabbccdef" and outputs a2b2c2def" or "a4bd2g4" for "aaaabddgggg".



#include<iostream>
#include<algorithm>
using namespace std;
int main()
{   int c;

    string s,temp;
    cin>>s;
    sort(s.begin(),s.end());
    for(int i=0;i<s.length();++i)
    {if(s[i]!=s[i+1])
    {
    c=count(s.begin(),s.end(),s[i]);
    cout<<s[i];
    if(c>1)
    {cout<<c;}
    }
    }
return 0;
}

Shortest Program to perform operation of Singly Linked List.

#include <iostream>
#include <list>
#include<stdlib.h>
using namespace std;
int main ()
{
  std::list<int> l;
  std::list<int>::iterator it;
  do
    {int c,d,n,pos;
    cout<<"\n\t\t Single Linked List Operations. \n 1.Insert \t 2.Delete \t 3.Display \t4.Exit.\n\n Enter Your Choice:";cin>>c;
    switch(c)
    {case 1: cout<<"\n\t Insert Operations\n\t 1.Begining \t 2.End \t 3.At a given position\nEnter your choice:";cin>>d;
    switch(d)
           {case 1:cout<<"\n Enter Element::";cin>>n;l.push_front(n);break;case 2:cout<<"\n Enter Element::";cin>>n;l.push_back(n);break;
            case 3:cout<<"\n Enter Element::";cin>>n;cout<<"\n Enter Position:";cin>>pos;it = l.begin();for(int i=0;i<pos-1;i++)++it;l.insert(it,n);break;
            default:cout<<"\n Wrong Choice.!!!";break;
           }break;
case 2:if(l.size()==0){cout<<"\nEmpty List.";break;}else{cout<<"\n Enter Position::";cin>>pos;it = l.begin();for(int i=0;i<pos-1;i++)++it;l.erase(it);break;}
case 3:if(l.size()==0){cout<<"\nEmpty List.";break;}else{for (it=l.begin(); it!=l.end(); ++it)std::cout << ' ' << *it<<"\n";break;}
case 4:exit(1);break;
default:cout<<"Wrong Choice!!!!\n";break;}
}while(1);
return 0;
}

Shortest Program to perform Stack Operations Using () Header File.

**This program may not run on Older Versions of GCC. Use 4.8.1 GCC Compiler to run this program.



#include<iostream>
#include<stack>
#include<cstdlib>
using namespace std;
int main()
{
    stack<int> s;
    int ch,n;
    cout<<"\n \t\t STACK OPERATIONS \n\n 1.PUSH \t2.POP\t 3.DISPLAY\t4.EXIT.\n\n Enter Your Choice::";
    cin>>ch;
    switch(ch)
    {
    case 1:cout<<"\n Element::";cin>>n;s.emplace(n);main();break;
    case 2:s.pop();main();break;
    case 3:for(int i=0;i<s.size();i++)
                 cout<<"\n"<<s.top();
           main();break;
    case 4:exit(0);
    default:cout<<"\n\t\n Wrong Choice !!";
            main();break;
    }
    return 0;
}

Wap to perform Single Linked List Operations.

#include<stdio.h>
#include<stdlib.h>
struct node
{
int info;
struct node *link;
};
struct node *start;

int ins_beg()
{
struct node *new_node;
new_node=(struct node*)malloc(sizeof(struct node));
printf("\n Enter the element:");
scanf("%i",&new_node->info);
if(start==NULL)
{
    new_node->link=NULL;
    start=new_node;
}
else
      {
            new_node->link=start;
            start=new_node;
      }
printf("\n Element Inserted sucessfully.\n");
main();
}
int ins_end()
{
    struct node *new_node,*lp;
new_node=(struct node*)malloc(sizeof(struct node));
printf("\n Enter the element:");
scanf("%i",&new_node->info);
if(start==NULL)
{
    new_node->link=NULL;
    start=new_node;
}
else
      {
            lp=start;
            while(lp->link!=NULL)
            {
                  lp=lp->link;
            }
            lp->link=new_node;
            new_node->link=NULL;
      }
printf("\n Element Inserted sucessfully.\n");
main();
}
int ins_pos()
{
struct node *new_node,*tptr;
int pos,i=0;
printf("\n Enter the position:");
scanf("%i",&pos);
if(pos==1)
    {ins_beg();
    main();}
else
{
tptr=start;
for(i=1;i<(pos-1)&&tptr!=NULL;i++)
    tptr=tptr->link;
if(tptr==NULL)
{printf("\n Invalid Position.");
    main();}
    else
    {   new_node=(struct node*)malloc(sizeof(struct node));
        printf("\n Enter the element:");
        scanf("%i",&new_node->info);
        new_node->link=tptr->link;
        tptr->link=new_node;
        printf("\n Item Inserted Sucessfully.");
        main();
    }
}
main();
}
int disp()
{
struct node *t;
if(start==NULL)
   {

    printf("\n List is empty.");
    return;
   }
t=start;
printf("\n Elements are:");
while(t!=NULL)
{
    printf("\n\n%i",t->info);
    t=t->link;
}
main();
}
int del()
{
int pos;
struct node *tptr,*ptr;
ptr=start;
printf("\n Enter the Position::");
scanf("%d",&pos);
if(pos==1)
{
 start=start->link;
}
else
{  int i=0;
    while(i<pos-1 && ptr!=NULL)
    {
        tptr=ptr;
        ptr=ptr->link;
        i++;
    }
    tptr->link=ptr->link;
}
main();
}


int main()
{
    do
    {
    int c,d;

    printf("\n\t\t Single Linked List Operations. \n 1.Insert \t 2.Delete \t 3.Display \t4.Exit.\n\n Enter Your Choice:");
    scanf("%d",&c);
    switch(c)
    {
    case 1:printf("\n\t Insert Operations\n\t 1.Begining \t 2.End \t 3.At a given position\nEnter your choice:");
           scanf("%d",&d);
           switch(d)
           {
               case 1:ins_beg();break;case 2:ins_end();break;case 3:ins_pos();break;default:printf("\n Wrong Choice.!!!");main();break;
           }

case 2:del();break;
case 3:disp();break;
case 4:exit(1);break;
default:printf("Wrong Choice!!!!\n");break;
    }
    }while(1);

    return 0;

}

Wap to compute the area of a isosceles triangle.

#include<stdio.h>
#include<math.h>
int main() {
 int a, b, c;
 float area, s;
 printf("Enter the sides of a triangle:\n");

 scanf("%d%d%d", &a, &b, &c);
 if ((a + b > c && a + c > b && b + c > a) && (a > 0 && b > 0 && c > 0)) {
  if (a == b || b == c || a == c) {
   s = (a + b + c) / 2.0;
   area = sqrt((s * (s - a) * (s - b) * (s - c)));
   printf("\nArea of an isosceles triangle is: %2f\n", area);
  } else {
   printf("\nTriangle is not an isosceles ");
  }
 } else {
  printf("\n Triangle formation not possible\n");
 }
 return 0;
}

WAP to classify the triangle as equilateral, isosceles and scalene.

#include<stdio.h>
#include<math.h>

int main() {

 int a, b, c;

 float s, area;

 printf("Enter the values of the sides of the triangle: \n");

 scanf("%d %d %d", &a, &b, &c);

 if ((a + b > c && a + c > b && b + c > a) && (a > 0 && b > 0 && c > 0))

 {

  s = (a + b + c) / 2.0;

  area = sqrt((s * (s - a) * (s - b) * (s - c)));

  if (a == b && b == c)

  {

   printf("Equilateral Triangle. \n");

   printf("Area of Equilateral Triangle is: %f", area);

  }

  else if (a == b || b == c || a == c)

  {

   printf("Isosceles Triangle. \n");

   printf("Area of an Isosceles Triangle: %f", area);

  }

  else

  {

   printf("Scalene Triangle. \n");

   printf("Area of Scalene Triangle: %f", area);

  }

 }

 else {
  printf("Triangle formation not possible");
 }

 return 0;
}

Print Your Name without using semicolon in program in C/C++

C

#include<stdio.h>
int main()
{
if(printf("Your Name"))
}


C++

#include<iostream>
using namespace std;
int main()
{
if(cout<<"Your Name")
return 0;
}

Infix to Post fix Conversion

#define SIZE 50            /* Size of Stack */
#include <ctype.h>
char s[SIZE];
int top = -1; /* Global declarations */

push(char elem) { /* Function for PUSH operation */
 s[++top] = elem;
}

char pop() { /* Function for POP operation */
 return (s[top--]);
}

int pr(char elem) { /* Function for precedence */
 switch (elem) {
 case '#':
  return 0;
 case '(':
  return 1;
 case '+':
 case '-':
  return 2;
 case '*':
 case '/':
  return 3;
 }
}

main() { /* Main Program */
 char infx[50], pofx[50], ch, elem;
 int i = 0, k = 0;
 printf("\n\nRead the Infix Expression ? ");
 scanf("%s", infx);
 push('#');
 while ((ch = infx[i++]) != '\0') {
  if (ch == '(')
   push(ch);
  else if (isalnum(ch))
   pofx[k++] = ch;
  else if (ch == ')') {
   while (s[top] != '(')
    pofx[k++] = pop();
   elem = pop(); /* Remove ( */
  } else { /* Operator */
   while (pr(s[top]) >= pr(ch))
    pofx[k++] = pop();
   push(ch);
  }
 }
 while (s[top] != '#') /* Pop from stack till empty */
  pofx[k++] = pop();
 pofx[k] = '\0'; /* Make pofx as valid string */
 printf("\n\nGiven Infix Expn: %s  Postfix Expn: %s\n", infx, pofx);
}

Stack Operations.

#include<stdio.h>
#include<stdlib.h>
#define SIZE 10
int item,i;
int push(int stack[SIZE],int &tos,int item)
{
   if(tos==SIZE-1)
        {printf("\n Stack Overflow.");

        }
   tos=tos+1;
   stack[tos]=item;
   return 0;
}
int pop(int stack[SIZE],int &tos)
{
int no;
if(tos==-1)
    printf("\n Stack is empty Cannot delete any Element...\n");
else
{no=stack[tos];
tos=tos-1;}
return 0;
}
int display(int stack[SIZE],int tos)
{   if(tos==-1)
    printf("\n Stack Is Empty......\n");
else{
     printf("\n Stack is:\n");
    for(i=tos;i>=0;i--)
    {    printf("\n __\n|");
        printf("%d",stack[i]);
        printf("|");}}
}
int main()
{
int ch,stack[SIZE],n;
static int tos=-1;
do
{
printf(" \n STACK OPERATIONS \n\t1.FILL STACK(before pushing) 2.PUSH\t 3.POP\t4.DISPLAY\t5.EXIT\n");
scanf("%d",&ch);
switch(ch)
{   case 1:printf("\n Enter the no of elements to be inserted:");
           scanf("%d",&n);
           printf("\n Enter elements:");
           for(i=0;i<n;i++)
            {scanf("%d",&stack[i]);tos++;}
            break;
    case 2:
            printf("\n Enter the element to be inserted:");
            scanf("%d",&item);
           push(stack,tos,item);
           break;
    case 3:
            pop(stack,tos);
            break;
    case 4:display(stack,tos);
           break;
    case 5:printf("\n Terminating......");
           exit(0);
           break;
    default:printf("\n Wrong Choice!!!");
    break;
}printf("\n Press Any Key to Continue.......\n ");


}while(n!=5);
return 0;
}

Program to find the transitive closure of a matrix using Warshall's Algorithm.

#include<stdio.h>
int i,j;
#define V 4
void transitiveClosure(int graph[V][V])
{
    int i, j, k;
    for (k = 0; k < V; k++)
    {
        for (i = 0; i < V; i++)
        {
          for (j = 0; j < V; j++)
            {
              graph[i][j] = graph[i][j] || (graph[i][k] && graph[k][j]);
            }
        }
    }
    printf ("Following matrix is transitive closure of the given graph\n");
    for ( i = 0; i < V; i++)
    {
        for ( j = 0; j < V; j++)
            printf ("%d ", graph[i][j]);
        printf("\n");
    }
}
int main()
{
    int graph[V][V] = { {1, 1, 0, 1},
                        {0, 1, 1, 0},
                        {0, 0, 1, 1},
                        {0, 0, 0, 1}
                      };
    transitiveClosure(graph);
    return 0;
}

Program to print the Union And Intersection of a Program.

#include<stdio.h>

void Union(int set1[10],int set2[10],int m,int n);
void Intersection(int set1[10],int set2[10],int m,int n);
int main()
{
 int a[10],b[10],m,n,i,j;
 int ch;

 printf("\nEnter the number of elements in first set:\n");
 scanf("%d",&m);
 printf("\nEnter the elements:\n");
 for(i=0;i<m;i++)
 {
  scanf("%d",&a[i]);
 }
 printf("\nElement of First set:\n\n");
 for(i=0;i<m;i++)
 {
  printf("%d\t",a[i]);
 }
 printf("\nEnter the number of elements in second set:\n");
 scanf("%d",&n);
 printf("\nEnter the elements:\n");
 for(i=0;i<n;i++)
 {
  scanf("%d",&b[i]);
 }
 printf("\nElement of second set\n");
 for(i=0;i<n;i++)
 {
  printf("%d\t",b[i]);
 }
 for(;;)
 {
  printf("\n\nMenu\n\n1.Union\n2.Intersection");
  printf("\n3.exit");
  printf("\nEnter your choice:\n");
  scanf("%d",&ch);
  switch(ch) {
  case 1:
   Union(a,b,m,n);
   break;
  case 2:
   Intersection(a,b,m,n);
   break;
  case 3:
   exit(0);
  }
  getch();
 }
}

void Union(int a[10],int b[10],int m,int n)
{
 int c[20],i,j,k=0,flag=0;
 for(i=0;i<m;i++)
 {
  c[k]=a[i];
  k++;
 }
 for(i=0;i<n;i++)
 {
  flag=0;
  for(j=0;j<m;j++)
  {
   if(b[i]==c[j])
   {
    flag=1;
    break;
   }
  }
  if(flag==0)
  {
   c[k]=b[i];
   k++;
  }
 }
 printf("\nElement of resultant set\n\n");
 for(i=0;i<k;i++)
 {
  printf("\t%d",c[i]);
 }
}
void Intersection(int a[10],int b[10],int m,int n)
{
 int c[20],i,j,k=0,flag=0;
 for(i=0;i<m;i++)
 {
  flag=0;
  for(j=0;j<n;j++)
  {
   if(a[i]==b[j])
   {
   c[k]=a[i];
   k++;

  }
 if(k==0)
 {
  printf("\n\nResultant set is null set!\n");
 }else{
  printf("\nElement of resultant set\n");
  for(i=0;i<k;i++)
  {
   printf("\t%d",c[i]);
  }

Count Number of Digits in N! factorial.

#include<stdio.h>
#include<math.h>

double count_digit(long a)
{
    double sum; long i;


    if(a==0)  return 1;
    else
    {
           sum=0;
     
        for(i=1;i<=a;i++)
                    sum+=log10(i);
        return floor(sum)+1;
    }
}

int main()
{
    double sum; long n;
    clrscr();
 
    while(scanf("%ld",&n)==1)
    {
        sum = count_digit(n);
        printf("%.0lf\n",sum);
    }  
    getch();
}

Printing all possible subsets using Bit Mask

#include<stdio.h>

void PrintAllSubset(int n)
{
int mask,pos,i,j,no = 1<<n;
for(i=1;i<no;i++)
 {
for(j=0;j<n;j++)
if((i&(1<<j)) > 0)
printf("%d ",j+1);
printf("\n");
}
}
int main()
{
int n;
while(scanf("%d",&n) == 1)
{
PrintAllSubset(n);
}
return 0;
}

Write a shortest program in C++ to sort a given array.

#include<iostream>

#include<algorithm>

using namespace std;

int main()

{

    int n;

   cin>>n;

  int arr[n];

    std::cout<<"\n Enter n elements in any order:";

    for(int i=0;i<n;i++)

        std::cin>>arr[i];

    std::sort(arr,arr+n);

    for(int i=0;i<n;i++)

        std::cout<<arr[i]<<" ";

    return 0;

}

Writing a Simple Program in C++ 4.3.2.

In Turbo C++ , we write a simple program as follows:-

#include<iostream.h>
#include<conio.h>

void main()
{clrscr();
int a;
cin>>a;
cout<<a;
getch();
}

But in latest C++ 4.3.2 Edition ,program is written as :-


#include<iostream>
using namespace std;
int main()
{
int a;
std::cin>>a;
std::cout<<a;
return 0;
}

• It is necessary to add  using namespace std; in the beginning of the program.
• (.h) is not written after a header file name.
• <conio.h>,<graphics.h> etc. are omitted header files in C++.
• A main function should return a value.

Or simply program could be written as:-

#include<iostream>
using namespace std;
int main()
{
int a;
cin>>a;
cout<<a;
return 0;
}

Input by Fastest Method

Header File:-#include<cstdio> (For c++)
#include<wchar.h> (For C)


Input for Character Variables :-

Use getchar_unlocked() for fastest input.
Eg.
char ch;
ch=getchar_unlocked();


Input for Integer Variables :-

Define a function that will take the input as:-


#define get getchar_unlocked
inline int fastinput( )
{
       int n = 0 , s = 1 ; char p = get( ) ;
       if( p == '-' ) s=-1;
     
       while( ( p < '0' || p > '9' ) && p != EOF && p != '-' )
          p = get( ) ;
       if( p == '-' )
       s = -1 , p = get( ) ;
       while( p >= '0' && p <= '9' )
       {
              n = ( n << 3 ) + ( n << 1 ) + ( p - '0' ) ;
              p = get( ) ;
       }
       return n * s ;
}