Issue with some simple logic and getting something to print C++ HouseWindowsLab

Question

Please Help. This simple program is suppose to calculate users inputs for how many of each house they want. Multiply it by the windows each house adds. And apply 1% more windows to the total for spares. Why isn't the spare part working?

/*************************************
* PROGRAM: WindowCalculator
* AUTHOR: Matthew Nickles
* DATE: 9/6/2018
* NOTES: This is for educational purposes, the program calculates
* how many windows for each house plan a city builder would get.
**************************************/

/* PREPROCESSOR COMMANDS */
#include <stdio.h>


/* MAIN PROCESSING CONTROL */
int main()
{
/* VARIABLE DECLARATIONS */
int MontgomeryHouses; /*20 Windows per a house*/
int KetteringHouses; /*15 Windows per a house*/
int SaxonHouses; /*12 Windows per a house*/
int TotalWindows; /*Total calculation of all windows*/
int SpareWindows; /*How many spare windows if you wanted 1% of total*/ 

/* WINDOWS PER HOUSE ALGORITHM */
printf("\n How many Montgomery Houses do you wish to build? They have 20             windows. ");
scanf("\n%d", &MontgomeryHouses);
fflush(stdin);

printf("\n How many Kettering Houses do you wish to build? They have 15 windows. ");
scanf("\n%d", &KetteringHouses);
fflush(stdin);

printf("\n How many Saxon Houses do you wish to build? They have 12 windows. ");
scanf("\n%d", &SaxonHouses);
fflush(stdin);

/* CALCULATE TOTAL WINDOWS*/
TotalWindows = (MontgomeryHouses * 20) + (KetteringHouses * 15)
        + (SaxonHouses * 12);
SpareWindows = TotalWindows * 0.01;
/* DISPLAY OUTPUT*/
printf("The spare windows needed &d are windows.\n",SpareWindows);
fflush(stdin);  
printf("\nThe total amount of windows needed for all houses are %d windows.\n",TotalWindows);
fflush(stdin);



return 0;
}
/* END OF PROGRAM */

Answer 1

Your logic is totally fine. It is just a tiny syntax error. In this line:

printf("The spare windows needed &d are windows.\n",SpareWindows);

&d should be replaced by %d.

I think you just overlooked it, because the other parts are perfect.

Answer 2

Your Problem is that ints cannot have numbers after a point. E.g: SpareWindows = 50.43, but because you declared it as int, it get truncated to 50. You might want to use floats instead, like:

/* VARIABLE DECLARATIONS */
int MontgomeryHouses; /*20 Windows per a house*/
int KetteringHouses; /*15 Windows per a house*/
int SaxonHouses; /*12 Windows per a house*/
int TotalWindows; /*Total calculation of all windows*/
float SpareWindows; /*How many spare windows if you wanted 1% of total*/ 

Since you total number of windows can always be just a "full" number, its perfectly fine to declare them as ints. But when moving to a percentage, like SpareWindows, you have to use floats. You might want to take a look here

Answer 3

Try this code:

#include <stdio.h>


/* MAIN PROCESSING CONTROL */
int main()
{
/* VARIABLE DECLARATIONS */
int MontgomeryHouses; /*20 Windows per a house*/
int KetteringHouses; /*15 Windows per a house*/
int SaxonHouses; /*12 Windows per a house*/
int TotalWindows; /*Total calculation of all windows*/
float SpareWindows; /*How many spare windows if you wanted 1% of total*/ 

/* WINDOWS PER HOUSE ALGORITHM */
printf("\n How many Montgomery Houses do you wish to build? They have 20             windows. ");
scanf("\n%d", &MontgomeryHouses);
fflush(stdin);

printf("\n How many Kettering Houses do you wish to build? They have 15 windows. ");
scanf("\n%d", &KetteringHouses);
fflush(stdin);

printf("\n How many Saxon Houses do you wish to build? They have 12 windows. ");
scanf("\n%d", &SaxonHouses);
fflush(stdin);

/* CALCULATE TOTAL WINDOWS*/
TotalWindows = (MontgomeryHouses * 20) + (KetteringHouses * 15)
        + (SaxonHouses * 12);
SpareWindows = (float)TotalWindows * 0.01; //Used Explicit type conversion to float
/* DISPLAY OUTPUT*/
printf("The spare windows needed %f are windows.\n",SpareWindows);
fflush(stdin);  
printf("\nThe total amount of windows needed for all houses are %d windows.\n",TotalWindows);
fflush(stdin);



return 0;
}
/* END OF PROGRAM */

Here actually the problem is when you try to multiply an integer by a decimal, output get converted to integer, so we must explicitly specify that value should be a float. Hope that worked.

Answer 4

There are multiple issues in your program.

Let me start to point out them one by one.

Consider: scanf("\n%d", &MontgomeryHouses);

Why you've used '\n' in the scanf() ? There is no need to use '\n' here when you are taking an input.

I see that you've used fflush(stdin); 5 times in your program. Stop using fflush(stdin) in your C programs. fflush() function should only be used for output stream. Read Standard streams to know more information about this. Use of fflush(stdin) is an Undefined behavior in both C & C++. Read the answers of these questions What does fflush(stdin) do in C programing? & Using fflush(stdin) for the more information.

Another issue is that you've written SpareWindows = TotalWindows * 0.01;. You want to use floating point value in SpareWindows variable but the data type of this variable is defined to be of type int. It should be defined as float SpareWindows; So you'll have to use '%f' format specifier to print the value of this variable.