Loop Control Structures – WHILE and DO-WHILE – Theory and Programs [Learn to code]

Understanding WHILE and DO-WHILE loop? Learn syntax for WHILE and DO-WHILE Loop and different programs on WHILE and DO-WHILE loop.

• 025. Write a Program to print numbers 1 to n using while loop in C language

  #include<stdio.h>
  #include<conio.h>   
  main()
  {
    int i=1,n;
    clrscr();
    printf("Enter n : ");
    scanf("%d",&n);
    while(i<=n)
    {
  	   printf("%d\t",i);
  	   i++;
    }
    getch();
  }
  
  
  

• 026. Write a Program to print numbers n to 1 using Do While loop in C language

  #include<stdio.h>
  #include<conio.h>   
  main()
  {
    int i=1,n;
    clrscr();
    printf("Enter n : ");
    scanf("%d",&n);
    i=n;
    do
    {
  	   printf("%d\t",i);
  	   i--;
    }while(i>=1);
    getch();
  }
  
  
  
  

• 027. Write a Program to print first n even numbers in C language

  #include<stdio.h>
  void main()
  {
      int i=1,n,counter=2;
      printf("Enter n : ");
      scanf("%d",&n);
    
      while(i<=n)
      {
          printf("%d\t",counter);
          counter = counter + 2;
          i++;
      }
  }
  

• 028. Write a Program to print first n odd numbers in C language

  #include<stdio.h>
  void main()
  {
      int i=1,n,counter=1;
      printf("Enter n : ");
      scanf("%d",&n);
   
      while(i<=n)
      {
          printf("%d\t",counter);
          counter = counter + 2;
          i++;
      }
  }
  

• 029. Write a Program to accept a number and print the number in reverse order. E.g. if 1324 is the number then the output will be 4231 in C language

  #include<stdio.h>
  #include<conio.h>  
  main()
  {
    int rem,n;
    clrscr();
    printf("Enter n : ");
    scanf("%d",&n);
    while(n>0)
    {
  	   rem=n%10;
  	   printf("%d",rem);
  	   n=n/10;
    }
    getch();
  }
  
  
  

• 030. Write a Program to accept a number and print sum of it’s digits in C language

  #include<stdio.h>
  #include<conio.h>  
  main()
  {
    int rem,sum=0,n
    clrscr();
    printf("Enter n : ");
    scanf("%d",&n);
    while(n>0)
    {
  	   rem=n%10;
  	   sum=sum+rem;
  	   n=n/10;
    }
    printf("Sum of digits....%d",sum);
    getch();
  }
  
  
  

• 031. Write a program to accept a number from user and check if it is Armstrong number or not i.e. 153 = 1^3 + 5^3 + 3^3 = 153 in C language

  #include
  #include
  main()
  {
    int temp,rem,sum=0,n;
    clrscr();
    printf("Enter n : ");
    scanf("%d", &n);
    temp=n;
    while(n > 0)
    {
  	   rem=n%10;
  	   sum=sum+rem*rem*rem;
  	   n=n/10;
    }
    if(temp==sum)
  		printf("Armstrong Number");
    else
  		printf("Not an Armstrong Number");
    getch();
  }