Iteration

  1. Change to following code to a while loop. 
    
int	x, y;
for (x=1; x < 57; x+= 2)
	y = x;

  2. What is wrong with the following? 
    
int	n=0;
while (n < 100)
	value = n*n;

  3. Write a while loop that calculates the sum of all numbers between 0 and 20 inclusive?

  4. Convert the above loop to a do ... while loop.

  5. Convert the above loop to a for loop.

  6. What is wrong with the following? 
    
i = 1;
while (i <= 10 )	
	cout << i;
	i++;

Answers 


































  1. 
x = 1;
while (x < 57)
{
	y = x;
	x += 2;
}
  2. The value of n within the loop is never incremented. It will therefore always have a value of 0, which is less than 100, and hence this will produce an infinite loop which will never terminate. The program will therefore never end. 

  3. int	i, sum =0;
i = 0;
while (i <= 100)
{
	sum += i;
	i++;
}

  4. int	i, sum =0;
i = 0;
do
{
	sum += i;
	i++;
}while (i <= 20);

  5. int	i, sum =0;
for (i=0; i <= 20; i++)
{
	sum += i;
}
  6. There are no braces around the cout and increment i statements, therefore it will execute only the cout statement within the loop, and an infinite loop will again occur.

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