Preliminary C programming

• Write a program to print "Hellow World".
  
  #include<stdio.h>
  #include<conio.h>
  void main()
  {
  clrscr();
  printf("Hellow World");
  getch();
  }
• The length and height of a rectangle and radius of a circle are input through the keyboard.Write a program to find the area & perimeter of the rectangle and circumference of the circle.
  #include<stdio.h>
  #include<conio.h>
  
  void main()
  {
   clrscr();
   int length,height,area,per,rad,cir;
   printf("Enter a length? \n");
   scanf("%d",&length);
   printf("Enter a height? \n");
   scanf("%d",&height);
   printf("Enter a radius?\n");
   scanf("%d",&rad);
  
   area=length*height;
  
   per=2*(length+height);
   cir=2*3.1416*rad;
   printf("The perimiter is: %d\n",per);
  
   printf("The area is: %d\n",area);
   printf("The circumference is:%d",cir);
  
   getch();
   }
• Rahim's basic salary is inpute through the keyboard.His house rent allowarnce is 30% of his basic salary and medical allowance is 5% of basic salary.He gets extra 1000 tk as technical allowance.Write a program to calculate his gross salary and print the result.
  
  #include<stdio.h>
  #include<conio.h>
  void main()
  {
  clrscr();
  int b,t,g;
  float h,m;
  printf("input rahim's basic salary:\n");
  scanf("%d",&b);
  h=(b*30)/100;
  m=(b*5)/100;
  t=1000;
  g=(b)+(h)+(m)+(t);
  printf("Rahim's gross salary is:%d",g);
  getch();
  }
• Two anumbers  are input  through the keyboard into two locations A and B. Write a program to interchange the contents of A and B.
  
  #include<stdio.h>
  #include<conio.h>
  void main()
  {
  clrscr();
  int a,b,temp;
  printf("Enter the value of A:");
  scanf("%d",&a);
  printf("Enter the value of B:");
  scanf("%d",&b);
  temp=a;
  a=b;
  b=temp;
  
  printf("\n\nAfter interchange the value of A is:%d",a);
  printf("\n\nAfter interchange the value of B is:%d",b);
  getch();
  }
• If a 5 digit number is input  through the keyboard, Write a program to calculate  and print  the sum of its digits.
  
  #include<stdio.h>
  #include<conio.h>
  void main()
  {
  clrscr();
  int rem,sum=0;
  int num;
  printf("A 5 digit number is?\n");
  scanf("%d",&num);
  rem=num%10;
  sum=rem+sum;
  num=num/10;
  rem=num%10;
  sum=rem+sum;
  num=num/10;
  rem=num%10;
  sum=rem+sum;
  num=num/10;
  rem=num%10;
  sum=sum+rem;
  num=num/10;
  sum=sum+num;
  printf("\nThe sum of the digits of this number is:%d",sum);
  getch();
  }
• If  a 5 digit number is input  through the keyboard, Write a program to reverse the number.
  
  #include<stdio.h>
  #include<conio.h>
  void main()
  {
  clrscr();
  long int rem,numb=0;
  long int num;
  printf("Enter the 5 digit number ?\n");
  scanf("%ld",&num);
  rem=num%10;
  numb=numb+(10000*rem);
  num=num/10;
  rem=num%10;
  numb=numb+(1000*rem);
  num=num/10;
  rem=num%10;
  numb=numb+(100*rem);
  num=num/10;
  rem=num%10;
  numb=numb+(10*rem);
  num=num/10;
  numb=numb+num;
  printf("The reverse number of this number is:%ld",numb);
  getch();
  }
• If  a 4 digit number is input  through the keyboard, Write a program to obtain the sum of the first and last digit of this number.
  #include<stdio.h>
  #include<conio.h>
  void main()
  {
  clrscr();
  int rem,sum=0;
  int num;
  printf("A 4 digit number is?\n");
  scanf("%d",&num);
  rem=num%10;
  sum=rem+sum;
  num=num/10;
  rem=num%10;
  num=num/10;
  rem=num%10;
  num=num/10;
  rem=num%10;
  sum=sum+rem;
  printf("\nThe sum of the first and last digit of this number is:%d",sum);
  getch();
  }