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;
}