Thread: C++ program problem..

Hey everyone. Got a question again that I've been racking my brain on trying to fix it and I haven't been able to yet. The program listed below has to do most of what the functions I have set say they do like get the highest balance, print the array, so on and so forth. I have a struct that has a double balance that seems to work fine when I use the function for highest balance but I get crazy math with the totalBalance function. For whatever reason I keep getting what i guess is a memory address or something. I have no idea why as everything else seems to work smoothly. If anyone could help me out I appreciate it. Any other advice on the program too is appreciate.

Oh. Also I have to print out something like student name, balance for the person with the highest balance. I know how to find the highest balance but really I'm lost on trying to use that to access the string name for that element. Thanks in advance.

Code:

#include <iostream>
#include <iomanip>
#include <string>

using namespace std;

//set constant for array size
const int SIZE = 100;

//declaring struct and it's variables
struct studentInfo {
	int studentAnumber;
	string studentName;
	double balance;
};

//Prototypes for functions
void getInfo(studentInfo student[], const int SIZE, int &count);

void searchString(studentInfo student[], int &count, int &leng);

void highestBalance(studentInfo student[], int &count, double &high);

void totalBalance(studentInfo student[], int &count, double &total);

void printArray(studentInfo student[], int &count, int &leng);

int main() {
	
	//declare array for struct studentInfo and initialize to constant size
	studentInfo students[SIZE];
	
         cout << "Welcome to the student account manager!" << endl;
	
	//declare and initialize counter variable and call function to get                                                                                         information input into array
         int counter = 0;
	getInfo(students, SIZE, counter);

	//call function to determine the length of the longest studentName in the array
        int length;
        searchString(students, counter, length);

	cout << "Length is now " << length << endl;

	//call function to determine the highest balance
        double highestBal;
        highestBalance(students, counter, highestBal);
        cout << "highest balance is " << fixed << showpoint << setprecision(2) << highestBal << endl;
	
       //call function to determine the total balance
       double totalBal;
       totalBalance(students, counter, totalBal);
       cout << "the total balance is " << fixed << showpoint << setprecision(2) << totalBal << endl;


	cout << "Report" << endl;
	cout << "------" << endl;
        cout << "A-NUMBER" << "    " << setw(length) << "NAME" << "BALANCE" << endl;

	printArray(students, counter, length);

    system("Pause");
	return 0;
}

void getInfo(studentInfo student[], const int SIZE, int &count) {
	
	for(int i = 1; i < SIZE + 1; i++) {
			//Ask user for A number, check for valid input
			cout << "Enter student " << i << " A number (or -999 to exit): ";
			cin >> student[i].studentAnumber;
			if (student[i].studentAnumber == -999) {
					break;
			}
			count = count + 1;
			while (cin.fail()) {
					cin.clear();
					cin.ignore(100,'\n');
					cout << "Invalid input. Please enter a valid A number: ";
					cin >> student[i].studentAnumber;
				}
			cin.ignore();
			//Ask user for student name. Getline for string
			cout << "Enter student " << i << " name: ";
//			cin >> students[i].studentName;
			getline(cin, student[i].studentName);
			
			//Ask user for balance, check for valid input
			cout << "Enter student " << i << " balance: ";
			cin >> student[i].balance;
				while (cin.fail()) {
					cin.clear();
					cin.ignore(100,'\n');
					cout << "Invalid input. Please enter a valid balance: ";
					cin >> student[i].balance;
				}
			cout << endl;
		}
	
}

void searchString(studentInfo student[], int &count, int &leng) {

	leng = student[0].studentName.length();

	for(int i = 0; i < count; i++) {
        if ( student[i].studentName.length() > leng ) {
            leng = student[i].studentName.length();
		}
	}
}


void highestBalance(studentInfo student[], int &count, double &high) {

	double temp = 0;
	
	for(int i = 0; i < count; i++) {
        if ( student[i].balance > temp ) {
            temp = student[i].balance;
            high = temp;
        }
   }

}

void totalBalance(studentInfo student[], int &count, double &total) {

	double temp = 0;

	for(int i = 0; i < count; i++) {
		temp = temp + student[i].balance;
		total = temp;
        }
}

void printArray(studentInfo student[], int &count, int &leng) {
	
	for(int i = count; i > 0; i--) { 
		cout << student[i].studentAnumber << "  " << setw(leng) << student[i].studentName << student[i].balance << endl;
	}
}

I'd love to use vectors and all but the teacher wants an array. It seems much simpler what you've written and makes sense but I have to stick to basically the format with the functions and array that I have

Originally Posted by Fandango21

I'd love to use vectors and all but the teacher wants an array. It seems much simpler what you've written and makes sense but I have to stick to basically the format with the functions and array that I have

If that's the case, it may be a good prank to write your own vector class(syntactically similar to std::vector...so the code remains portable) which uses arrays internally and use it in every opportunity you get !

I'm feeling generous. I fixed your code (somewhat) but I will tell you what you had wrong so you know in the future.

2 main problems: using reference parameters when you have no intention of changing their values is BAD. Use pass-by-value or const references. That way you avoid hard to find bugs.

The other is not using the (int i = 0; i < N; ++i) idiom; not using it is a good way to get off-by-one errors which you had.

Other than that, the program is well-coded.

Code:

#include <iostream>
#include <iomanip>
#include <string>
#include <cstdlib> // for system()

using namespace std;

//set constant for array size
const int SIZE = 100;

//declaring struct and it's variables
struct studentInfo {
	int studentAnumber;
	string studentName;
	double balance;
};

//Prototypes for functions

/** CHANGED **/
void getInfo(studentInfo student[], int size, int &count);

/** CHANGED **/
void searchString(studentInfo student[], int count, int &leng);

/** CHANGED **/
void highestBalance(studentInfo student[], int count, double &high);

/** CHANGED **/
void totalBalance(studentInfo student[], int count, double &total);

/** CHANGED **/
void printArray(studentInfo student[], int count, int leng);

int main() {

	//declare array for struct studentInfo and initialize to constant size
	studentInfo students[SIZE];

         cout << "Welcome to the student account manager!" << endl;

	//declare and initialize counter variable and call function to get                                                                                         information input into array
         int counter = 0;
	getInfo(students, SIZE, counter);

    cout << "Counter is " << counter << endl;
	//call function to determine the length of the longest studentName in the array
        int length;
        searchString(students, counter, length);

	cout << "Length is now " << length << endl;

	//call function to determine the highest balance
        double highestBal;
        highestBalance(students, counter, highestBal);
        cout << "highest balance is " << fixed << showpoint << setprecision(2) << highestBal << endl;

       //call function to determine the total balance
       double totalBal;
       totalBalance(students, counter, totalBal);
       cout << "the total balance is " << fixed << showpoint << setprecision(2) << totalBal << endl;

    system("pause");
	cout << "Report" << endl;
	cout << "------" << endl;
        cout << "A-NUMBER" << "    " << setw(length) << "NAME" << "BALANCE" << endl;

	printArray(students, counter, length);

    system("Pause");
	return 0;
}

void getInfo(studentInfo student[], int size, int &count) {

	for(int i = 0; i < size; i++) { // <-- always do this way (avoids off by one errors)
			//Ask user for A number, check for valid input
			cout << "Enter student " << i+1 << " A number (or -999 to exit): ";
			cin >> student[i].studentAnumber;
			if (student[i].studentAnumber == -999) {
					break;
			}
			count = count + 1;
			while (cin.fail()) {
					cin.clear();
					cin.ignore(100,'\n');
					cout << "Invalid input. Please enter a valid A number: ";
					cin >> student[i].studentAnumber;
				}
			cin.ignore();
			//Ask user for student name. Getline for string
			cout << "Enter student " << i << " name: ";
//			cin >> students[i].studentName;
			getline(cin, student[i].studentName);

			//Ask user for balance, check for valid input
			cout << "Enter student " << i << " balance: ";
			cin >> student[i].balance;
				while (cin.fail()) {
					cin.clear();
					cin.ignore(100,'\n');
					cout << "Invalid input. Please enter a valid balance: ";
					cin >> student[i].balance;
				}
			cout << endl;
		}

}

void searchString(studentInfo student[], int count, int &leng) {

	leng = student[0].studentName.length();

	for(int i = 1; i < count; i++) {
        if ( student[i].studentName.length() > leng ) {
            leng = student[i].studentName.length();
		}
	}
}


void highestBalance(studentInfo student[], int count, double &high) {

	high = student[0].balance;

	for(int i = 1; i < count; i++) {
        if ( student[i].balance > high ) {
            high = student[i].balance;
        }
   }
}

void totalBalance(studentInfo student[], int count, double &total) {
    total = 0;
	for(int i = 0; i < count; i++) {
		total += student[i].balance;
        }
}

void printArray(studentInfo student[], int count, int leng) {

	for(int i = 0; i < count; ++i) {
		cout << student[i].studentAnumber << "  " << setw(leng) << student[i].studentName << student[i].balance << endl;
	}
}

Thanks for mentioning the constant references, I forgot and they will definitely help avoid future confusion and bugs. I found my off by one error only like 10 minutes ago. Wish I would have remembered I changed that in the getInfo function. As for the (int i = 0; i < N; ++i), That's all we've used up to this point so I don't know of another method to cycle through things. What would you suggest using instead? I appreciate the help and I'm still plugging along trying to get better so I definitely take any advice I can get. Also, any suggestions on my second problem? I still have no clue how to go about it. I have the highestBalance function that finds the highest balance in the array of structs but I also need to get the string Name of that same element in the array and output it like this. "The highest balance is : " John Doe " , $500.00. Thanks again!

Thanks Andrew. That's what I just modified the highestBalance function to do. It returns the index and now I can use that outside to print what I needed. Thanks everyone for the help!