if/else and printf questions

[chip.litch]

I can't seem to figure out why my if / else series will not print. When I compile I get warnings, but no errors. It will let me run the program but stops after returning total hours. All help and suggestions are greatly appreciated.

#include<stdio.h>

#define low 5.151
#define medium 7.110
#define high 9.800

int getUserInput ( );
int getTotalKWH (end_mtr, start_mtr);
float calculateTheBill (bill);

int main ( )       
{
		int cust_num = 0;
		int start_mtr = 0;
		int end_mtr = 0;
		int hours = 0;
		float bill = 0;

		printf ("This program will compute BetterJoules Electric Company Customer Bills");

		printf ("\n\nPlease enter Customer Number: ");
		
			cust_num = getUserInput ( );

		printf ("\n\nPlease enter starting meter reading:  ");
		
			start_mtr = getUserInput ( );

		printf ("\n\nPlease enter ending meter reading:  ");
		
			end_mtr = getUserInput ( );

			hours = getTotalKWH (end_mtr, start_mtr);

			bill = calculateTheBill (hours, cust_num, end_mtr, hours, bill );

		return (0);		

}

int getUserInput ( )
{
		int input = 0;

		scanf ("%d%*c", &input);

		return input;

}

int getTotalKWH (int end_mtr, int start_mtr)
{
		int hours = 0;

		hours = end_mtr - start_mtr;

		printf("\n\nTotal Kilowatt Hours used: %d ", hours);

		scanf ("%d%*c", &hours);

		return hours;

}
float calculateTheBill (int cust_num, int hours, int end_mtr, int start_mtr)
{
		float bill = 0;

		
			if( hours <= 300 ) {
				bill == (hours*low)/100;
				scanf ("%.2f", &bill);
			}
			else if( hours <= 500 ) {
				bill == (300*low + (end_mtr - 301)*medium)/100;
				scanf ("%.2f", &bill);	
			}
			else if (hours > 500) {
				bill == (300*low + 199*medium + (end_mtr -501)*high)/100;
				scanf ("%.2f", &bill);
			}

		printf ("\n\n Cusomer %d's total bill is $%.2f", cust_num, bill);
		
		return bill;
	}

[laserlight]

I am guessing that in calculateTheBill() you want to compute the bill and store it in bill rather than compare bill to the result of some computation, and then read in into bill.

[tabstop]

if( hours <= 300 ) {
				bill == (hours*low)/100;
				scanf ("%.2f", &bill);
			}

What do you think this is supposed to do? == does not do assigning, only comparing, and of course scanf doesn't print anything out at all.

Also, you pass your arguments to calculateTheBill in the wrong order.

[chip.litch]

I am guessing that in calculateTheBill() you want to compute the bill and store it in bill rather than compare bill to the result of some computation, and then read in into bill.

yes, that is what I am looking to do. i was very happy when I compiled and I got no errors. I thought I had done something correct. this stuff is eating my lunch. thanks for the help