Thread: Sum of steps

I want to build a program so that it will sum integers from any "start" to "finish" spaced by a "step". Negative step values are allowed. For invalid combinations, i.e. “step” = 0, start less than finish with a negative step, or start bigger than finish with a positive step; I want the program to terminate and print an error message.

Code:

/* Sum of Spaced Integers */
/* Ian Richardson */
/* 02/14/2003 */
#include <stdio.h>

int main (void)		
{
	/* intialization phase */
int count, start, step, end, sum = 0;
	printf("What is your starting number?\n");
	scanf("%d", &start);
	
	printf("What is your ending number?\n");
	scanf("%d", &end);
	
	printf("What interval step would you like to use?\n");
	scanf("%d", &step);
	
	if ( step > 0 )
	else if ( step < 0 )
	else if ( start < end && step > 0 )
	else if ( start > end && step < 0 ) {
	
	for ( count = start; count <= end; count += step ) {
	sum += count;
	}
	printf("The start number is: %d\n", start );
	printf("The end number is: %d\n", end );
	printf("The sum of the spaced integers is: %d\n", sum );
	}
	else
	printf("Error: Invalid step entered.\n");
	
	return 0;
}

if step < 0 error
if start >= end error

Otherwise, just process as normal. Done in a single line:

Code:

if( step < 0 || start >= end )
{
    error
}
else
{
    do valid steps here
}

You basicly had the logic worked out already, you just didn't make it do anything.

Quzah.