DaniWeb Forum Index > Software Development > C++

C++ RSS

help with functions please

Please support our C++ advertiser: Intel Parallel Studio Home

•

Join Date: Mar 2008

Posts: 61

Reputation: anbuninja is an unknown quantity at this point

Solved Threads: 0

anbuninja

Offline

Junior Poster in Training

help with functions please

Feb 24th, 2009

so im starting the second half of my c++ class and we are getting into functions. are first assignment and im already stuck -__-

the teacher gives us the code for above main so we just need to write the prototypes.

heres my code so far (prototypes probably wrong) it builds but doesnt run.

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
#include <string>
using namespace std;
 
void getHours(int, string);
void getMinutes(int, string);
void calcTotalTime (/* complete */);
bool isValidMinutes (/* complete */);
bool isValidHours(/* complete */);
const int MAX_MINS = 59;
const int MAX_HOURS = 23;
const int MIN_MINS = 0;
const int MIN_HOURS = 0;
 
int main ()
{
    int hours, minutes, addedHours, addedMinutes;
    getHours(hours, "Enter the number of hours for the starting time: ");
    getMinutes(minutes, "Enter the number of minutes for the starting time: ");
    getHours (addedHours, "Enter the number of hours to be added to the starting time: ");
    getMinutes (addedMinutes,  "Enter the number of minutes to be added to the starting time: ");
    calcTotalTime (hours, minutes, addedHours, addedMinutes);
    cout << "\nThe total time is " << hours << " hours and "
            << minutes << " minutes." << endl;
	system("pause");
    return 0;
}
 
 
[B]void getHours(int &input1, string &hours)
{
 
	cout << hours;
	cin >> input1;
}
 
void getMinutes(int &input2, string &minutes)
{
	cout << minutes;
	cin >> input2;
}[/B]
#include <iostream>
#include <string>
using namespace std;

void getHours(int, string);
void getMinutes(int, string);
void calcTotalTime (/* complete */);
bool isValidMinutes (/* complete */);
bool isValidHours(/* complete */);
const int MAX_MINS = 59;
const int MAX_HOURS = 23;
const int MIN_MINS = 0;
const int MIN_HOURS = 0;
 
int main ()
{
    int hours, minutes, addedHours, addedMinutes;
    getHours(hours, "Enter the number of hours for the starting time: ");
    getMinutes(minutes, "Enter the number of minutes for the starting time: ");
    getHours (addedHours, "Enter the number of hours to be added to the starting time: ");
    getMinutes (addedMinutes,  "Enter the number of minutes to be added to the starting time: ");
    calcTotalTime (hours, minutes, addedHours, addedMinutes);
    cout << "\nThe total time is " << hours << " hours and "
            << minutes << " minutes." << endl;
	system("pause");
    return 0;
}


[B]void getHours(int &input1, string &hours)
{
	
	cout << hours;
	cin >> input1;
}

void getMinutes(int &input2, string &minutes)
{
	cout << minutes;
	cin >> input2;
}[/B]

need help with the bold parts etc.. im really confuse on writing the prototypes

heres how its supposed to run
Enter the number of hours for the starting time: 12
Enter the number of minutes for the starting time: 44
Enter the number of hours to be added to the starting time: 3
Enter the number of minutes to be added to the starting time: 18

The total time is 16 hours and 2 minutes.

help!

Last edited by Ancient Dragon; Feb 25th, 2009 at 8:11 pm. Reason: add line numbers

•

Join Date: Aug 2005

Posts: 15,413

Reputation: Ancient Dragon has a reputation beyond repute

Solved Threads: 1470

Ancient Dragon Ancient Dragon is offline

Offline

Still Learning

Re: help with functions please

Feb 24th, 2009

The prototypes do not match the actual functions. Compare them and you will see what's wrong. After that you should realize that you can't pass string literals as you did to those functions -- must pass a reference to std::string object.

Last edited by Ancient Dragon; Feb 24th, 2009 at 9:18 pm.

Don't PM me with questions -- you might get a nasty PM in response. If you have a question then post it in one of the forums.

•

Join Date: Mar 2008

Posts: 61

Reputation: anbuninja is an unknown quantity at this point

Solved Threads: 0

anbuninja

Offline

Junior Poster in Training

Re: help with functions please

Feb 25th, 2009

hmm still confused

am i close?

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
void getHours (string& getHours, int& hours)
{
	cout << getHours;
	cin >> hours;
}
void getHours (string& getHours, int& hours)
{
	cout << getHours;
	cin >> hours;
}

help me atleast on this one then i can get an idea and try to do the rest

•

Join Date: Aug 2005

Posts: 15,413

Reputation: Ancient Dragon has a reputation beyond repute

Solved Threads: 1470

Ancient Dragon Ancient Dragon is offline

Offline

Still Learning

Re: help with functions please

Feb 25th, 2009

What you just posted is incorrect. You can not have the name of a parameter the same as the name of the function. You will get a compiler error on that.

Look at line 5 of the code you originally posted. Notice the two parameters are an int and a string. Now look at the parameters in on line 30 -- the parameters are a reference to an int, and a reference to a string. Change the function prototype on line 5 to look like the function header located on line 30. All you have to do is copy from line 30 and paste on line 5.

Last edited by Ancient Dragon; Feb 25th, 2009 at 8:15 pm.

Don't PM me with questions -- you might get a nasty PM in response. If you have a question then post it in one of the forums.

•

Join Date: Mar 2008

Posts: 61

Reputation: anbuninja is an unknown quantity at this point

Solved Threads: 0

anbuninja

Offline

Junior Poster in Training

Re: help with functions please

Feb 25th, 2009

okay right now all i want is to get a successful build just on getHours and getMinutes.

i did what u told me (i think) and still get 2 errors

code so far

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
#include <string> 
using namespace std;
 
 
 
void getHours(int &hours, string &getHours);
void getMinutes(int &minutes, string& getMinutes);
//void calcTotalTime (/* complete */);
//bool isValidMinutes (/* complete */);
//bool isValidHours(/* complete */);
const int MAX_MINS = 59;
const int MAX_HOURS = 23;
const int MIN_MINS = 0;
const int MIN_HOURS = 0;
 
int main ()
{
    int hours, minutes, addedHours, addedMinutes;
    getHours(hours, "Enter the number of hours for the starting time: ");
    getMinutes(minutes, "Enter the number of minutes for the starting time: ");
    //getHours (addedHours, "Enter the number of hours to be added to the starting time: ");
    //getMinutes (addedMinutes,  "Enter the number of minutes to be added to the starting time: ");
    //calcTotalTime (hours, minutes, addedHours, addedMinutes);
    cout << "\nThe total time is " << hours << " hours and "
            << minutes << " minutes." << endl;
	system("pause");
    return 0;
}
 
 
 
void getHours (int& hours, string& getHours)
{
	cout << getHours;
	cin >> hours;
}
 
void getMinutes (int& minutes, string& getMinutes)
{
	cout << getMinutes;
	cin >> minutes;
}
#include <iostream>
#include <string> 
using namespace std;



void getHours(int &hours, string &getHours);
void getMinutes(int &minutes, string& getMinutes);
//void calcTotalTime (/* complete */);
//bool isValidMinutes (/* complete */);
//bool isValidHours(/* complete */);
const int MAX_MINS = 59;
const int MAX_HOURS = 23;
const int MIN_MINS = 0;
const int MIN_HOURS = 0;
 
int main ()
{
    int hours, minutes, addedHours, addedMinutes;
    getHours(hours, "Enter the number of hours for the starting time: ");
    getMinutes(minutes, "Enter the number of minutes for the starting time: ");
    //getHours (addedHours, "Enter the number of hours to be added to the starting time: ");
    //getMinutes (addedMinutes,  "Enter the number of minutes to be added to the starting time: ");
    //calcTotalTime (hours, minutes, addedHours, addedMinutes);
    cout << "\nThe total time is " << hours << " hours and "
            << minutes << " minutes." << endl;
	system("pause");
    return 0;
}



void getHours (int& hours, string& getHours)
{
	cout << getHours;
	cin >> hours;
}

void getMinutes (int& minutes, string& getMinutes)
{
	cout << getMinutes;
	cin >> minutes;
}

•

Join Date: Mar 2008

Posts: 61

Reputation: anbuninja is an unknown quantity at this point

Solved Threads: 0

anbuninja

Offline

Junior Poster in Training

Re: help with functions please

Feb 25th, 2009

so i have to change the names on these to something else

void getHours (int& hours, string& getHours)
{
cout << getHours;
cin >> hours;
}

would something like (int& input1, string& s)
{
cout << s;
cin >> input1;
}

work?

•

Join Date: Oct 2008

Posts: 40

Reputation: seanhunt is an unknown quantity at this point

Solved Threads: 6

seanhunt

Offline

Light Poster

Re: help with functions please

Feb 25th, 2009

the second example would work, assuming that you declare:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
void getHours(int& input1, string& s);
void getHours(int& input1, string& s);

at the top and the definition is:

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
void getHours(int& input1, string& s)
{
cout << s;
cin >> input1;
}
void getHours(int& input1, string& s)
{
cout << s;
cin >> input1;
}

•

Join Date: Aug 2007

Posts: 1,678

Reputation: vmanes is a splendid one to behold

Solved Threads: 193

vmanes

Offline

Posting Virtuoso

Re: help with functions please

Feb 25th, 2009

•

Originally Posted by Ancient Dragon

What you just posted is incorrect. You can not have the name of a parameter the same as the name of the function. You will get a compiler error on that.

Actually, you can have the same name for the function and one of its parameters. The scope of the parameter is local to the function, and it masks the function name.

Now this would be awkward if trying to write a recursive function....

Everyone's gotta believe in something. I believe I'll have another drink.
~~~~~~~~~~~~~~~~~~
Looking for an exciting graduate degree? Robotics and Intelligent Autonomous Systems (RIAS) at SDSM&T See the program brochure here.

•

Join Date: Mar 2008

Posts: 61

Reputation: anbuninja is an unknown quantity at this point

Solved Threads: 0

anbuninja

Offline

Junior Poster in Training

Re: help with functions please

Feb 25th, 2009

alright i did that still get the same errors

cannot convert parameter 2 from const char to string

my code

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
#include <iostream>
#include <string> 
using namespace std;
 
 
 
void getHours(int& input1, string& s);
void getMinutes(int& input2, string& s);
//void calcTotalTime (/* complete */);
//bool isValidMinutes (/* complete */);
//bool isValidHours(/* complete */);
const int MAX_MINS = 59;
const int MAX_HOURS = 23;
const int MIN_MINS = 0;
const int MIN_HOURS = 0;
 
int main ()
{
    int hours, minutes, addedHours, addedMinutes;
    getHours(hours, "Enter the number of hours for the starting time: ");
    getMinutes(minutes, "Enter the number of minutes for the starting time: ");
    //getHours (addedHours, "Enter the number of hours to be added to the starting time: ");
    //getMinutes (addedMinutes,  "Enter the number of minutes to be added to the starting time: ");
    //calcTotalTime (hours, minutes, addedHours, addedMinutes);
    cout << "\nThe total time is " << hours << " hours and "
            << minutes << " minutes." << endl;
	system("pause");
    return 0;
}
 
 
 
void getHours (int& input1, string& s)
{
	cout << s;
	cin >> input1;
}
 
void getMinutes (int& input2, string& s)
{
	cout << s;
	cin >> input2;
}
#include <iostream>
#include <string> 
using namespace std;



void getHours(int& input1, string& s);
void getMinutes(int& input2, string& s);
//void calcTotalTime (/* complete */);
//bool isValidMinutes (/* complete */);
//bool isValidHours(/* complete */);
const int MAX_MINS = 59;
const int MAX_HOURS = 23;
const int MIN_MINS = 0;
const int MIN_HOURS = 0;
 
int main ()
{
    int hours, minutes, addedHours, addedMinutes;
    getHours(hours, "Enter the number of hours for the starting time: ");
    getMinutes(minutes, "Enter the number of minutes for the starting time: ");
    //getHours (addedHours, "Enter the number of hours to be added to the starting time: ");
    //getMinutes (addedMinutes,  "Enter the number of minutes to be added to the starting time: ");
    //calcTotalTime (hours, minutes, addedHours, addedMinutes);
    cout << "\nThe total time is " << hours << " hours and "
            << minutes << " minutes." << endl;
	system("pause");
    return 0;
}



void getHours (int& input1, string& s)
{
	cout << s;
	cin >> input1;
}

void getMinutes (int& input2, string& s)
{
	cout << s;
	cin >> input2;
}

•

Join Date: Aug 2005

Posts: 15,413

Reputation: Ancient Dragon has a reputation beyond repute

Solved Threads: 1470

Ancient Dragon Ancient Dragon is offline

Offline

Still Learning

Re: help with functions please

#10

Feb 25th, 2009

•

Originally Posted by anbuninja

alright i did that still get the same errors

cannot convert parameter 2 from const char to string

Your function prototype is correct now. Next you need to realize that you can not pass a string literal to those functions because the functions expect a reference to a std::string object.

There are a couple ways to fix that:
1) remove the reference operator from the function prototype and the actual function. I see no reason to pass the string by reference anyway. But I understand your instructor wants it that way, so maybe that is not an option for you.

2) Typecase the string leterals

Help with Code Tags

(Toggle Plain Text)

getHours(hours, "Enter the number of hours for the starting time: ");
    getMinutes(minutes, (string)("Enter the number of minutes for the starting time"));

3) split the string literals out

 Help with Code Tags 
 C++ Syntax (Toggle Plain Text) 
std::string prompt;
prompt = Enter the number of minutes for the starting time.";
getMinutes(minutes, prompt);
 
std::string prompt;
prompt = Enter the number of minutes for the starting time.";
getMinutes(minutes, prompt);