need explenatino to why my toupper is not working

[TJBELTRan]

So in my code I am trying to obtain first and last name of the user as well as the address city etc. but once obtained I need to make the first and last name uppercase as well as the state my program runs but I guess I am not using the "toupper" correctly can anyone guide to what I am doing wrong pleasw

 #define _CRT_SECURE_NO_WARNINGS
#include <iostream>
#include <iomanip>
#include <cstring>
#include <cctype>
#include "graph1.h"
using namespace std;

//Prototypes are below:
char* getString(char* prompt);
bool validateName(char* name);
bool validateAddress(char* address);
bool validateCity(char* city);
bool validateState(char* state);
bool validateZip(char* zip);
char* convertToUpper(char* string);
void displayLetter(char* fn, char* ln, char* addr, char* city, char* state, char* zip, int weight);


int main()
 {
	//Variable Declaration/Initialization
	char* firstName = NULL;
	char* lastName = NULL;
	char* address = NULL;
	char* phone = NULL;
	char* city = NULL;
	char* state = NULL;
	char* upperState = NULL;
	char* zip = NULL;
	bool res = false;
	int weight = 0;
	char *upperfirstName = NULL;
	char *upperlastName = NULL;



	//Display graphics window
	displayGraphics();

	//Get the fields - validate based on function
	do
	{
		/*   Get the first name*/
		firstName = getString("Enter First Name: ");

		//validate the name
		res = validateName(firstName);
		upperfirstName = convertToUpper(firstName);


	} while (!res);

	do
	{
		/*   Get the last name*/
		lastName = getString("Enter Last Name: ");

		//validate the name
		res = validateName(lastName);
		upperlastName = convertToUpper(lastName);
	} while (!res);

	do
	{
		//Get the address
		address = getString("Enter Street Address: ");

		//validate the address
		res = validateAddress(address);

	} while (!res);

	do
	{
		//Get the phone
		city = getString("Enter City: ");

		//validate the city 
		res = validateCity(city);

	} while (!res);

	do
	{
		//Get the phone
		state = getString("Enter State: ");

		//validate the phone
		res = validateState(state);
		upperState = convertToUpper(state);

	} while (!res);

	do
	{
		//Get the zipcode
		zip = getString("Enter Zipcode: ");

		//validate the zipcode
		res = validateZip(zip);

	} while (!res);


	cout << endl << endl << endl;

	cout << "Enter Weight";
	cin >> weight;



	//Display the fields
	displayLetter(firstName, lastName, address, city, state, zip, weight);

	return 0;
}




char* getString(char* prompt)
{
	char* cptr = NULL;
	char buffer[255];
	cout << prompt;

	cin.getline(buffer, sizeof(buffer));
	cptr = new char[strlen(buffer) + 1];

	strcpy(cptr, buffer);
	return (cptr);



}

bool validateName(char* name)
{
	int i = 0;
	//for to validate the name 
	for (i = 0; name[i] != NULL; i++)
	{
		if (!isalpha(name[i]))
			return false;
		



	}
}




bool validateAddress(char* address)
{
	int i = 0;
	//for to validate the name 
	for (i = 0; address[i] != NULL; i++)
	{
		if ((!isalnum(address[i])) && (!isspace(address[i])))

			return false;
	}
}






bool validateCity(char* city)
{
	int i = 0;
	//for to validate the name 
	for (i = 0; city[i] != NULL; i++)
	{
		if (!isalpha(city[i]) && isupper(!city[0]))
			return false;


	}

}
bool validateState(char* state)
{
	int i = 0;
	//for to validate the name 
	for (i = 0; state[i] != NULL; i++)
	{
		if (!isalpha(state[i]))
			return false;



	}

}
bool validateZip(char* zip)
{
	int i = 0;
	//for to validate the name 
	for (i = 0; zip[i] <6; i++)
	{
		if (!isdigit(zip[i]))


			return false;

	}

}



char* convertToUpper(char* string)
{
	int i;

	//for loop use to conver into uppercase 
	for (i = 0; string[i] != NULL; i++)
	{
		if (!isupper(string[i]))
		{
			toupper(string[i]);
			
		}
	}
	return string;

}
void displayLetter(char* first, char* last, char* addr, char* city, char* upperState, char* zip, int weight)
{
	int x = 525, y = 20;
	double cost;
	int x1 = 200, y1 = 385, width = 290, height = 85;
	displayBMP("envelope.bmp", 0, 0);
	displayBMP("returnAddress.bmp", 43, 26);
	gout << setPos(315, 210) << first << endg;
	gout << setPos(365, 210) << last << endg;
	gout << setPos(315, 220) << addr << endg;
	gout << setPos(315, 230) << city << endg;
	gout << setPos(385, 230) << upperState << endg;
	gout << setPos(410, 230) << zip << endg;


	for (int i = 0; i < weight; i++)
	{
		displayBMP("stamp.bmp", x, y);




		if (i == 2)
		{
			x = 600;
			y = y + 80;
		}

		x = x - 75;


		cost = weight*0.47;

		gout << setPos(x1 + 10, y1 + 20) << "Weight: " << weight << " ounces" << endg;
		gout << setPos(x1 + 10, y1 + 40) << "Cost Of First Class Stamp: 47 Cents" << endg;
		gout << setPos(x1 + 10, y1 + 60) << "Total Mailing Cost: $" << cost << endg;

		drawLine(x1, y1, (x1 + width), y1, 1);//top line across
		drawLine(x1, y1, x1, (y1 + height), 1);//left vertical line
		drawLine((x1 + width), (y1), (x1 + width), (y1 + height), 1);//right vertical line
		drawLine((x1), (y1 + height), (x1 + width), (y1 + height), 1);//bottom line across



	}
}

[Chervil]

Line 226 toupper(string[i]);
you call the function toupper() but don't do anything with the value returned by the function. You should assign the result to some variable. I suggest
string[i] = toupper(string[i]);

[TJBELTRan]

Ok thanks Chervil that worked I can't believe it was that simple but if I could quick question if for example on the name I just wanted the First letter to just be capatalized how would I go about doing that?

[Chervil]

Well, the first letter would be string[0], you wouldn't need a loop for that. Though if the string was already upper case in whole or in part, you might want to convert the string to lower case first, then change the first character to upper.