Calculate Average of Four Numbers in C++

//Write a Program to calculate average of four numbers

#include <iostream.h>

#include <conio.h>

void main ()

{

int a,b,c,d,avg;

clrscr ();

cout <<"Enter 5 Numbers";

cin >>a >>b >>c >>d;

avg =(a+b+c+d)/4;

cout <<"\n Average is: "<<avg;

getch ();

}

Addition of two numbers in C++

//Write a Programa Addition of Two Numbers

#include <iostream.h>

#include <conio.h>

void main ()

{

int a,b,c;

clrscr ();

cout <<" Enter A: ";

cin >>a;

cout <<" Enter B: ";

cin >>b;

c= a+b;

cout <<"\n Addition is: "<<c;

getch ();

}

Copy One File to Another

/* Write a C program which copies one file to another.*/

#include <stdio.h>

#include <conio.h>

#include <process.h>

void main(int argc, char *argv[])

{

 FILE *fs,*ft;

 char ch;

 clrscr();

 if(argc!=3)

 {

  puts("Invalid number of arguments.");

  exit(0);

  }

 fs = fopen(argv[1],"r");

 if(fs==NULL)

 {

 puts("Source file cannot be opened.");

 exit(0);

 }

 ft = fopen(argv[2],"w");

 if (ft==NULL)

 {

 puts("Target file cannot be opened.");

 fclose(fs);

 exit(0);

 }

 while(1)

 {

  ch=fgetc(fs);

  if (ch==EOF)

  break;

  else

  fputc(ch,ft);

  }

  fclose(fs);

  fclose(ft);

  getch();

}

Reverse First Letter characters

/* Write a C program to reverse the first n characters in a file.

(Note: The file name and n are specified on the command line.)*/

#include <stdio.h>

#include <conio.h>

#include <string.h>

#include <process.h>

void main(int argc, char *argv[])

{

  char a[15];

  char s[20];

  char n;

  int k;

  int j=0;

  int i;

  int len;

  FILE *fp;

  if(argc!=3)

  {

  puts("Improper number of arguments.");

  exit(0);

  }

  fp = fopen(argv[1],"r");

  if(fp == NULL)

  {

  puts("File cannot be opened.");

  exit(0);

  }

  k=*argv[2]-48;

  n = fread(a,1,k,fp);

  a[n]='\0';

  len=strlen(a);

  for(i=len-1;i>=0;i--)

  {

   s[j]=a[i];

   printf("%c",s[j]);

   j=j+1;

}

s[j+1]='\0';

getch();

}