C Programming, User input Multiplication to calculate KWHrs

#1 · 04-11-2013 08:24PM #1

I need help because for the life of me I cannot figure this out,

Basically I need to end up with C programming for this pseudocode

"input number of rooms:

for each room in house

input wattage of lights:
input number of hours use/day (average)
calculate kWHrs for room per year
sumkWHrs_lights

input number of TV/Computers

for each TV/computer/gaming device in house

input wattage
input number of hours/day (average)
calculate kWHrs for year
sumkWHrs_TV_Computers

Total_kWHrs = sum kWHrs_lights + sum kWHrs_TV_Computers etc etc..

I've been trying to multiply out the first part and I cannot get it to work any way at all.
Here's My Attempt

{int NumRooms = 0;
int counter;
float RoomWatts, LightHours, LightKWhrs=0;
float SumHours=0, SumWatts=0;
printf ("Enter number of rooms in your house: ");
scanf ("%d", &NumRooms);

counter = 1;
while (counter <= NumRooms)
{
printf ("Enter Total Light Watts and The Hours Use of The Lights Per Day in Room %d :", counter);
scanf ("%f %f", &RoomWatts, &LightHours);
LightKWhrs= ((SumWatts)*(SumHours)) +((RoomWatts)*(LightHours));
counter++;
}

printf("Your total Kilowatt Hours consumed by lights is %f kWhrs \n\n", LightKWhrs);

}

Scuba_Scoper · 05-11-2013 11:03AM

matt.finn wrote: »

float RoomWatts, LightHours, LightKWhrs=0;

Hint: Three variables I do declare, only 1 has value

Hint2: take a tutorial on debugging and inspecting values.

matt.finn · 05-11-2013 12:21PM

Cheers, Ill try that now.

Think I have a new way figured to do it using functions anyway.

Scuba_Scoper · 05-11-2013 12:46PM

matt.finn wrote: »

Cheers, Ill try that now.

Think I have a new way figured to do it using functions anyway.

good man - keep at it... the only way in the beginning is to keep trying until you get it.. then after 20 or 30 programs you realise that design is where you need to take your time with - everything else flows from that. Top Down step wise refinement... ahhh the memories.

matt.finn · 07-11-2013 06:42PM

How would I code so that each input is multiplied and adds to the next

I want to add up all the kwhrs usage in the house?

I just can't seem to figure it out and it's driving me towards insanity!!

Talisman · 07-11-2013 07:11PM

You start with an input variable numRooms and a subTotal (initialised to 0.0).

int numRooms;
float subTotal = 0.0f;

for (iteration=1; iteration <= numRooms; iteration++) {
  subTotal += getKWHrs(iteration);
}

The getKWHrs function would return the total for the room and it gets added to the subTotal.

You can build similar functionality into the code of the function to process each appliance - if you store the appliance types in an array then you iterate through the array prompting for a value for each and add it to the sub total for that room.

matt.finn · 07-11-2013 10:51PM

Ah cheers, You have no idea how much that helps me now!

Appreciate it!

matt.finn · 08-11-2013 01:46PM

Anyone able to figure problems with this? After the 1st run through the loop it stops?
I need to add the figures for each room to get LightKWhrs and I need to do this for every electric appliance in my house by monday so help needed asap!!

if(choice==2) //Choice is = Bottom_Up_Approach
{
int NumRooms = 0;
int counter=0;
float RoomWatts=0.0;
float LightHours=0.0;
float LightKWhrs=0.0;
//float SumHours=1.0;
//float SumWatts=2.0;
printf ("Enter number of rooms in your house: ");
scanf_s ("%d", &NumRooms);
if (NumRooms <=0)
{
printf ("This is impossible, Value must be >=0 \n");
return;
}
for(counter=0;counter<=NumRooms;counter++)
{
printf ("Enter Total Light Watts and Hours Usage Of Lights in Room %d :",(counter+1));
scanf_s("%.2f %.2f ", &RoomWatts, &LightHours);

if (RoomWatts <0.0)
{
printf ("This is impossible, Value must be >=0 \n");
return;
}

if (LightHours<0.0)
{
printf ("This is impossible, Value must be >=0 \n");
return;
}
LightKWhrs= LightKWhrs+(RoomWatts*LightHours);
printf("test...\n");
}

printf("Your total Kilowatt Hours consumed by lights is %f kWhrs \n\n", LightKWhrs);
}

}

Talisman · 08-11-2013 03:26PM

scanf_s("%.2f %.2f ", &RoomWatts, &LightHours);

%.2f is for output : It displays 2 decimal places

For input you use %f. It doesn't matter whether the user enters a value with a decimal point or not, the input will be treated as a float.

Also you have a bug in your for loop, it will loop once more than required:

for(counter=0;counter<=NumRooms;counter++)

Either change the counter to initially be 1 or change the condition to be less than NumRooms.

Another thing you should do is specify to the compiler that the initial values of the variables are of type float - put f immediately after the declared value. If you don't put the f, then the compiler may assume that the value is a double and add extra code to cast the value to a float at runtime.

float RoomWatts=0.0f;
float LightHours=0.0f;
float LightKWhrs=0.0f;

matt.finn · 08-11-2013 07:39PM

I think I have it got now, Got a decent amount of help off a classmate today.

C Programming, User input Multiplication to calculate KWHrs

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