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Having trouble pointing to a structure

jbs4bmx (5)
Hello, I am sorry if this is such a simple fix, but I have a bad habit of making things harder for myself. I am having trouble with pointers and currently have a program that will not work for me. I get the errors on lines 40 and 41.
I am not sure where I am going wrong as this is the third or fourth way that I have tried to initialize my pointer. Any help is appreciated. Thanks!
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/******************************************************************************************/
/*                                                                                        */
/*                             Programmer: Jason Smith                                    */
/*                                                                                        */
/*                           CSC 134 --> C++ Programming                                  */
/*                                                                                        */
/*                              non-Chapter Homework                                      */
/*                                                                                        */
/*                                    Program 4                                           */
/*                                                                                        */
/******************************************************************************************/

// Program Headers/Libraries
#include <iostream>
#include <cstdlib>
#include <string>
#include <math.h>

using namespace std;

struct building
{
	double length;
	double width;
	double height;
}unit;

////////// /* Function Prototypes */ //////////
double calc_area(double unit);
double num_wins(double &total);
double calc_BTU(double unit);

//////////////////// /* Main body of program */ ////////////////////
int main()
{
		
	//Variables Used in Program
	std::string name, grade;
	double coats, brush, gallon, grand, total, negative, window, BTU=0;
	double *ptr;
	building *ptr;
		
	//Obtain User Data
	cout<<"Welcome, Please enter your FIRST NAME: ";
	cin>>name;
	system("CLS"); //Clear Screen and start with new page.

	cout<<"Thank you "<<name<<".\n\n***** We are now ready for your buildings measurements. *****\n";
	cout<<"Please enter the length in feet. "; cin>>unit.length;
	cout<<"Please enter the width in feet. "; cin>>unit.width;
	cout<<"Please enter the height in feet. "; cin>>unit.height;
	cout<<"\n\n***** Now we need to know how many coats of paint will be applied. ******\n";
	cout<<"Please enter the number of coats that will be applied. "; cin>>coats;
	system("CLS"); // Clears screen for a new page again.

	//Calling Functions and Performing Other Calculations
	total = calc_area(*ptr);
	window = num_wins(total);
	BTU = calc_BTU(*ptr);
	negative = total-(window * 18);
	grand = negative*coats;
	brush = ceil(grand/1100);
	gallon = ceil(grand/325);
	
	//Determine the Cooling Unit Class.
	if (BTU > 0 && BTU < 14500)
	{
		grade = "A";
	}
	else if (BTU >= 14501 && BTU <= 29500)
	{
		grade = "B";
	}
	else if (BTU >= 29501 && BTU <= 45000)
	{
		grade = "C";
	}
	else if (BTU >= 45001 && BTU <= 61000)
	{
		grade = "D";
	}
	else if (BTU >= 61001 && BTU <= 75000)
	{
		grade = "E";
	}
	else if (BTU >= 75001 && BTU <= 100000)
	{
		grade = "F";
	}
	else if (BTU >= 100001)
	{
		grade = "G";
	}
	
	//Display all results to User.
	cout<<"Thank you "<<name<<". Here is your list of supplies.\n\n";
	cout<<"Total surface area: "<<negative<<"sqft"<<endl;
	cout<<"Number of coats: "<<coats<<endl;
	cout<<"Number of brushes required: "<<brush<<endl;
	cout<<"Gallons of paint required: "<<gallon<<endl;
	cout<<"Number of windows needed: "<<window<<endl;
	cout<<"The BTUs required to cool the unit are: "<<BTU<<endl;
	cout<<"Your recommended Cooling Unit is Grade "<<grade<<"."<<endl;
	cout<<endl;
	system("PAUSE");
	return 0;
}



//////////////////// /* Function for calculating surface area. */ ////////////////////
double calc_area(double building)
{
	double wall1, wall2, wall3, wall4, total;

	wall1 = unit.length*unit.height;
	wall2 = unit.length*unit.height;
	wall3 = unit.width*unit.height;
	wall4 = unit.width*unit.height;
	total = wall1+wall2+wall3+wall4;
	return total; //return variable 'total'
}



//////////////////// /* Function for calculating number of windows. */ ////////////////////
double num_wins(double &total)
{
	double window;
	window = ceil(total/150);
		if ((int)(window) %2==0) // Cast double as int to check for mod 2 remainder of zero and if a remainder is present, it will add 1 to window.
		{	
			window = window;
		}
		else
		{	
			window++;
		}
	return window; //return variable 'window'
}



//////////////////// /* Function for calculating number of BTUs. */ ////////////////////
double calc_BTU(double building)
{
	double cubicArea, BTU;
	cubicArea = (unit.length * unit.height * unit.width);
	BTU = cubicArea/1000;
	return BTU;
}
vlad from moscow (6539)
You may not define the same name for several objects in the same declarative region

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	double *ptr;
	building *ptr;
.
Last edited on
jbs4bmx (5)
Thank you for the quick reply... I'm not entirely sure what you mean but it gives me a good base on which to start. Just need to do some more research and studying. :)
vlad from moscow (6539)
The both declarations declare the same name for objects of different types. So the compiler does not know how to consider name ptr either as a pointer to double or a pointer to building.
jbs4bmx (5)
Thanks vlad from moscow --> you helped me to find the answer on my own and helped me learn the accurate way to declare pointers.

building *ptr = new building;
This line replaced the two lines (40,41) and fixed my pointer issues.

I now get issues with:

Prog4-JS.obj : error LNK2019: unresolved external symbol "double __cdecl calc_BTU(struct building)" (?calc_BTU@@YANUbuilding@@@Z) referenced in function _main

Been searching for an answer to what exactly this means but have not been able to find one so far. This is my edited code if you're interested:

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/******************************************************************************************/
/*                                                                                        */
/*                             Programmer: Jason Smith                                    */
/*                                                                                        */
/*                           CSC 134 --> C++ Programming                                  */
/*                                                                                        */
/*                              non-Chapter Homework                                      */
/*                                                                                        */
/*                                    Program 4                                           */
/*                                                                                        */
/******************************************************************************************/

// Program Headers/Libraries
#include <iostream>
#include <cstdlib>
#include <string>
#include <math.h>
using namespace std;
/*******************************************************************************************************************************************************/
struct building
{
	double length;
	double width;
	double height;
}unit;
/*******************************************************************************************************************************************************/
////////// /* Function Prototypes */ //////////
double calc_area(building);
double num_wins(double &total);
double calc_BTU(building);
/*******************************************************************************************************************************************************/
//////////////////// /* Main body of program */ ////////////////////
int main()
{
		
	//Variables Used in Program
	std::string name, grade;
	double coats, brush, gallon, grand, total, negative, window, BTU=0;
	building *ptr = new building;
		
	//Obtain User Data
	cout<<"Welcome, Please enter your FIRST NAME: ";
	cin>>name;
	system("CLS"); //Clear Screen and start with new page.
	
	cout<<"Thank you "<<name<<".\n\n***** We are now ready for your buildings measurements. *****\n";
	cout<<"Please enter the length in feet. "; cin>>unit.length;
	cout<<"Please enter the width in feet. "; cin>>unit.width;
	cout<<"Please enter the height in feet. "; cin>>unit.height;
	cout<<"\n\n***** Now we need to know how many coats of paint will be applied. ******\n";
	cout<<"Please enter the number of coats that will be applied. "; cin>>coats;
	system("CLS"); // Clears screen for a new page again.

	//Calling Functions and Performing Other Calculations
	total = calc_area(unit);
	window = num_wins(total);
	BTU = calc_BTU(unit);
	negative = total-(window * 18);
	grand = negative*coats;
	brush = ceil(grand/1100);
	gallon = ceil(grand/325);
	
	//Determine the Cooling Unit Class.
	if (BTU > 0 && BTU < 14500)
	{
		grade = "A";
	}
	else if (BTU >= 14501 && BTU <= 29500)
	{
		grade = "B";
	}
	else if (BTU >= 29501 && BTU <= 45000)
	{
		grade = "C";
	}
	else if (BTU >= 45001 && BTU <= 61000)
	{
		grade = "D";
	}
	else if (BTU >= 61001 && BTU <= 75000)
	{
		grade = "E";
	}
	else if (BTU >= 75001 && BTU <= 100000)
	{
		grade = "F";
	}
	else if (BTU >= 100001)
	{
		grade = "G";
	}
	
	//Display all results to User.
	cout<<"Thank you "<<name<<". Here is your list of supplies.\n\n";
	cout<<"Total surface area: "<<negative<<"sqft"<<endl;
	cout<<"Number of coats: "<<coats<<endl;
	cout<<"Number of brushes required: "<<brush<<endl;
	cout<<"Gallons of paint required: "<<gallon<<endl;
	cout<<"Number of windows needed: "<<window<<endl;
	cout<<"The BTUs required to cool the unit are: "<<BTU<<endl;
	cout<<"Your recommended Cooling Unit is Grade "<<grade<<"."<<endl;
	cout<<endl;
	system("PAUSE");
	return 0;
}
/*******************************************************************************************************************************************************/
//////////////////// /* Function for calculating surface area. */ ////////////////////
double calc_area(double *ptr)
{
	double wall1, wall2, wall3, wall4, total1;

	wall1 = unit.length*unit.height;
	wall2 = unit.length*unit.height;
	wall3 = unit.width*unit.height;
	wall4 = unit.width*unit.height;
	total1 = wall1+wall2+wall3+wall4;
	return total1; //return variable 'total'
}
/*******************************************************************************************************************************************************/
//////////////////// /* Function for calculating number of windows. */ ////////////////////
double num_wins(double &total)
{
	double window=0;
	window = ceil(total/150);
		if ((int)(window) %2==0) // Cast double as int to check for mod 2 remainder of zero and if a remainder is present, it will add 1 to window.
		{	
			window = window;
		}
		else
		{	
			window++;
		}
	return window; //return variable 'window'
}
/*******************************************************************************************************************************************************/
//////////////////// /* Function for calculating number of BTUs. */ ////////////////////
double calc_BTU(double *ptr)
{
	double cubicArea, code;
	cubicArea = (unit.length * unit.height * unit.width);
	code = cubicArea/1000;
	return code;
}
Last edited on
jbs4bmx (5)
NVM all... I just ended up removing the pointers and the program works.
I do not have to involve pointers but wanted to just so I could learn them get used to using them.

Thanks for all the help. I will definitely continue to use this forum for my future learning needs. :)
vlad from moscow (6539)
You declared function calc_BTU as

double calc_BTU(building);

but defined it as

double calc_BTU(double *ptr)


So when you call it as

BTU = calc_BTU(unit);

where unit has type building the compiler does not find its definition.



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