Thread: While loop question!

Code:

 
#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main()
float fact;

/* what number do we want to calculate the factorial of? */
num = 10;

/* Initialise the factorial */
fact = 1.0;

/* Count from 2 to num, multiply fact by counter each time */
i = 2;
while ( i <= num) {
   fact = fact *  i;
i = i + 1;
}

/* Print the result */
printf (“The factorial of &#37;d is %f\n”, num, fact);
}

The point of that was to calculate the factorial of 10, using a while loop, which worked fine, but I have this question that says Alter the program so that the counter counts from num down to 1, rather than the other way .

I tried altering the code in the following way but it didn’t work:

Code:

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int main()
float fact;

/* what number do we want to calculate the factorial of? */
num = 10;

/* Initialise the factorial */
fact = 1.0;

/* Count from 10 to num, multiply fact by counter each time */
i = 10;
while ( 0< i <= num) {
   fact = fact *  i;
i = i - 1;
}

/* Print the result */
printf (“The factorial of %d is %f\n”, num, fact);
}

Which should give me the same answer as the first code written but it doesn’t. Where have I gone wrong?

Thanks!

Code:

while ( 0< I <= num)

This doesn't do what you think it does.

It means you're not telling the compiler what i is. The same goes for num. The compiler can't just guess "oh, i is an int, num is also an int" you have to declare to the compiler that they are.

In code :

Code:

int i;
int num;

> While(0<l && l<=num)

Capital i, or any case of L are terrible names for variables. It's also while() not While()

0 < I <= num, is the same as, i E(0,num], in other words

Code:

if(i > 0 && i <= num)
    /* in range */