Programming Questions

It is also called as post tested loop. It is used when it is necessary to execute the loop at least one time. Syntax:

do {
Loop body
} while (Expression);

Example:

int main(){
    int num,i=0;  
    do{
         printf("To enter press 1\n");
         printf("To exit press  2");
         scanf("%d",&num);
         ++i;
         switch(num){
             case 1:printf("You are welcome\n");break;
             default : exit(0);
         }
    }
    while(i<=10);
    return 0;
}

Output: 3 3 4 4

Output: 1 1 1 1 1 1
For loop will execute six times.

Note: continue keyword in do-while loop bring the program its while condition (while(0)) which is always false.

 #include<stdio.h>
int main(){
  int i=1,f=1,num;

  printf("Enter a number: ");
  scanf("%d",&num);

  while(i<=num){
      f=f*i;
      i++;
  }

  printf("Factorial of %d is: %d",num,f);
  return 0;
}

Sample output:
Enter a number: 5
Factorial of 5 is: 120

#include<stdio.h>
int main(){
  FILE *p,*q;
  char file1[20],file2[20];
  char ch;
  printf("\nEnter the source file name to be copied:");
  gets(file1);
  p=fopen(file1,"r");
  if(p==NULL){
      printf("cannot open %s",file1);
      exit(0);
  }
  printf("\nEnter the destination file name:");
  gets(file2);
  q=fopen(file2,"w");
  if(q==NULL){
      printf("cannot open %s",file2);
      exit(0);
  }
  while((ch=getc(p))!=EOF)
      putc(ch,q);
  printf("\nCOMPLETED");
  fclose(p);
  fclose(q);
 return 0;
}

Output may vary from compiler to compiler.

The order of evaluation of the arguments to a function call is unspecified.

#include<stdio.h>
int main(){
  int num,i,f,r,sum=0,temp;

  printf("Enter a number: ");
  scanf("%d",&num);
 
  temp=num;
  while(num){
      i=1,f=1;
      r=num%10;

      while(i<=r){
         f=f*i;
        i++;
      }
      sum=sum+f;
      num=num/10;
  }
  if(sum==temp)
      printf("%d is a strong number",temp);
  else
      printf("%d is not a strong number",temp);

  return 0;
}

Sample output:
Enter a number: 145
145 is a strong number

Constant expression required in the second case, we cannot use j.