#include<iostream.h>
#include<graphics.h>
#include<conio.h>
class fifo_alg
{
    char ref[100];
    int frame,fault,front,rear,x,y;
    char *cir_que;
public:
    fifo_alg()
    {
 front=rear=-1;
 fault=0;
 x=5,y=50;
    }
    void getdata();
    void insert(char ch);
    void chart();
    void page_fault();
};
void fifo_alg::getdata()
{
    cout<<"Enter Page reference string : ";
    cin.getline(ref,50);
    cout<<"Enter no. of frames : ";
    cin>>frame;
}
void fifo_alg::chart()
{
   char d[2];
   int f=front,r=rear,flag=1;
   for(int i=0;i<frame;i++)
   {
      if(f==r&&flag==0)
      {
  d[0]=0;
  if(f==frame)
    f=0;
      }
      else
      {
   if(f==r)
      flag=0;
   d[0]=cir_que[f];
   f=(f+1)%frame;
   d[1]=0;
      }
      rectangle(x,y+i*20,x+20,y+(i+1)*20);
      outtextxy(x+10,y+i*20+10,d);
   }
   x+=20;
}
void fifo_alg::insert(char ch)
{
    if(front==-1)
    {
 cir_que[0]=ch;
 front=0,rear=0;
    }
    else
    {
 rear=(rear+1)%frame;
 cir_que[rear]=ch;
    }
    fault++;
}
void fifo_alg::page_fault()
{
    cir_que=new char[frame];
    int flag=0;
    for(int i=0;ref[i]!=0;i++)
    {
 if(ref[i]>57||ref[i]<48)
     continue;
 if(front==-1)
     insert(ref[i]);
 else
 {
     if(cir_que[rear]==ref[i])
  flag=1;
     else
     {
  for(int y=front;y!=rear;y=(y+1)%frame)
     if(cir_que[y]==ref[i])
     {
   flag=1;
   break;
     }
     }
     if(flag==0)
     {
  if((rear+1)%frame==front)
      front=(front+1)%frame;
  insert(ref[i]);
     }
 }
 if(flag==0)
    chart();
 flag=0;
    }
    cout<<"Number of page faults : "<<fault;
}
int main()
{
    fifo_alg page;
    page.getdata();
    int gdriver = DETECT,gmode;
    initgraph(&gdriver, &gmode, "");
    page.page_fault();
    getch();
    return 0;
}

C++ Online Compiler

Write, Run & Share C++ code online using OneCompiler's C++ online compiler for free. It's one of the robust, feature-rich online compilers for C++ language, running on the latest version 17. Getting started with the OneCompiler's C++ compiler is simple and pretty fast. The editor shows sample boilerplate code when you choose language as C++ and start coding!

Read inputs from stdin

OneCompiler's C++ online compiler supports stdin and users can give inputs to programs using the STDIN textbox under the I/O tab. Following is a sample program which takes name as input and print your name with hello.

#include <iostream>
#include <string>
using namespace std;

int main() 
{
    string name;
    cout << "Enter name:";
    getline (cin, name);
    cout << "Hello " << name;
    return 0;
}

About C++

C++ is a widely used middle-level programming language.

  • Supports different platforms like Windows, various Linux flavours, MacOS etc
  • C++ supports OOPS concepts like Inheritance, Polymorphism, Encapsulation and Abstraction.
  • Case-sensitive
  • C++ is a compiler based language
  • C++ supports structured programming language
  • C++ provides alot of inbuilt functions and also supports dynamic memory allocation.
  • Like C, C++ also allows you to play with memory using Pointers.

Syntax help

Loops

1. If-Else:

When ever you want to perform a set of operations based on a condition If-Else is used.

if(conditional-expression) {
   //code
}
else {
   //code
}

You can also use if-else for nested Ifs and If-Else-If ladder when multiple conditions are to be performed on a single variable.

2. Switch:

Switch is an alternative to If-Else-If ladder.

switch(conditional-expression){    
case value1:    
 // code    
 break;  // optional  
case value2:    
 // code    
 break;  // optional  
......    
    
default:     
 code to be executed when all the above cases are not matched;    
}

3. For:

For loop is used to iterate a set of statements based on a condition.

for(Initialization; Condition; Increment/decrement){  
  //code  
}

4. While:

While is also used to iterate a set of statements based on a condition. Usually while is preferred when number of iterations are not known in advance.

while (condition) {  
// code 
}

5. Do-While:

Do-while is also used to iterate a set of statements based on a condition. It is mostly used when you need to execute the statements atleast once.

do {  
 // code 
} while (condition);

Functions

Function is a sub-routine which contains set of statements. Usually functions are written when multiple calls are required to same set of statements which increases re-usuability and modularity. Function gets run only when it is called.

How to declare a Function:

return_type function_name(parameters);

How to call a Function:

function_name (parameters)

How to define a Function:

return_type function_name(parameters) {  
 // code
}