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Apr 7th, 2009

How do I write a C++ program that converts from 24-hour notation to 12-hour notation?

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I need help in writing a C++ program that converts 24-hour notation to 12-hour notation. (For example, it should convert 14:25 to 2:25 P.M. The input is given as two integers. There are three functions: one for input, one to do the conversion, and one for output. Record the A.M./P.M. information as a value of type char, 'A' for A.M. and 'P' for P.M. Thus, the function for doing the conversions will have a call-by-reference formal parameter of type char to record whether it is A.M. of P.M. ) Specifically, I need help iin defining the function : int convertTo12Hour(int hours, char& type)
The code I have so far is:

C++ Syntax (Toggle Plain Text)
#include <iostream>
using namespace std;
 
 
void input(int& hours, int& minutes);
void output(int hours, int minutes, char type);
int convertTo12Hour(int hours, char& type);
 
int main() {
  int hours;
  int minutes;
  char type;
  char answer;
 
  do
   {
    input(hours, minutes);
    hours = convertTo12Hour(hours, type);
    output(hours, minutes, type);
 
    cout << "Perform another calculation? (y/n): ";
    cin >> answer;
 
    } while ((answer == 'Y') || (answer == 'y'));
 
  return 0;
}
 
void input(int& hours, int& minutes) {
  cout << "Enter the hours for the 24 hour time: ";
  cin >> hours;
  cout << "Enter the minutes for the 24 hour time: ";
  cin >> minutes;
 }
//
// Displays a time in 12 hour notation
//
void output(int hours, int minutes, char type) {
  cout << "The time converted to 12 hour format is: " << hours << ":";  
  //
  // special handling for leading 0s on the minutes
  //
  cout.width(2);
  cout.fill('0');
  cout << minutes;
  //
  if (type == 'A')
    cout << " A.M." << endl;
  else
    cout << " P.M." << endl;
 }
 
int convertTo12Hour(int hours, char& type);{
#include <iostream>
using namespace std;


void input(int& hours, int& minutes);
void output(int hours, int minutes, char type);
int convertTo12Hour(int hours, char& type);

int main() {
  int hours;
  int minutes;
  char type;
  char answer;
 
  do
   {
    input(hours, minutes);
    hours = convertTo12Hour(hours, type);
    output(hours, minutes, type);

    cout << "Perform another calculation? (y/n): ";
    cin >> answer;

    } while ((answer == 'Y') || (answer == 'y'));

  return 0;
}
 
void input(int& hours, int& minutes) {
  cout << "Enter the hours for the 24 hour time: ";
  cin >> hours;
  cout << "Enter the minutes for the 24 hour time: ";
  cin >> minutes;
 }
//
// Displays a time in 12 hour notation
//
void output(int hours, int minutes, char type) {
  cout << "The time converted to 12 hour format is: " << hours << ":";  
  //
  // special handling for leading 0s on the minutes
  //
  cout.width(2);
  cout.fill('0');
  cout << minutes;
  //
  if (type == 'A')
    cout << " A.M." << endl;
  else
    cout << " P.M." << endl;
 }
 
int convertTo12Hour(int hours, char& type);{

but i am stuck on the rest am i on the right track and where do i go from here ?

rock9449

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Apr 7th, 2009

Re: How do I write a C++ program that converts from 24-hour notation to 12-hour notation?

First do the math on paper & pencil. Once you get that right then coding it will be simple.

If the hours is greater than 12 just subtract 12 and the A.M./P.M. flag will be 'P'. Otherwise if the hours is less than 12 the flag will be 'A' and you don't have to do anything to the hours.

Last edited by Ancient Dragon; Apr 7th, 2009 at 9:45 am.

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Apr 7th, 2009

Re: How do I write a C++ program that converts from 24-hour notation to 12-hour notation?

where do i insert this into my code perhaps i outdid myself and should start all over , am i on the right track?

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Apr 7th, 2009

Re: How do I write a C++ program that converts from 24-hour notation to 12-hour notation?

put it in the convert function that you started (see the last line that you posted)

int convertTo12Hour(int hours, char& type);{
Delete that semicolon!

Last edited by Ancient Dragon; Apr 7th, 2009 at 9:49 am.

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Re: How do I write a C++ program that converts from 24-hour notation to 12-hour notation?

using an if else statement but what function i call i can put it in words but that's where i have a hard problem putting it into code
i know it would be something like
if hours < 12
pm = 12- hours ?
cout>>pm?

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Re: How do I write a C++ program that converts from 24-hour notation to 12-hour notation?

Click to Expand / Collapse Quote originally posted by Ancient Dragon ...

First do the math on paper & pencil. Once you get that right then coding it will be simple.

If the hours is greater than 12 just subtract 12 and the A.M./P.M. flag will be 'P'. Otherwise if the hours is less than 12 the flag will be 'A' and you don't have to do anything to the hours.

Maybe you can avoid that, I am thinking something like this.

C++ Syntax (Toggle Plain Text)
void Convert( int& hours )
{
	hours = hours % 12;
 
}
void Convert( int& hours )
{
	hours = hours % 12;

}

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Apr 7th, 2009

Re: How do I write a C++ program that converts from 24-hour notation to 12-hour notation?

Click to Expand / Collapse Quote originally posted by BevoX ...

Maybe you can avoid that, I am thinking something like this.
C++ Syntax (Toggle Plain Text)
void Convert( int& hours )
{
	hours = hours % 12;
 
}
void Convert( int& hours ) { hours = hours % 12; }

The problem is that will not tell whether it's am or pm.

Last edited by Ancient Dragon; Apr 7th, 2009 at 10:02 am.

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Re: How do I write a C++ program that converts from 24-hour notation to 12-hour notation?

Error 1 error LNK2019: unresolved external symbol "int __cdecl convertTo12Hour(int,char &)" (?convertTo12Hour@@YAHHAAD@Z) referenced in function _main lab4.obj lab4
Error 2 fatal error LNK1120: 1 unresolved externals C:\Documents and Settings\oml5000\My Documents\Visual Studio 2008\Projects\lab4\Debug\lab4.exe lab4

it almost works but im still getting two compiler errors something with regards to my conversion

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Apr 7th, 2009

Re: How do I write a C++ program that converts from 24-hour notation to 12-hour notation?

yeah i see the problem that's why i think its giving me a compiler error so after the convert statement i think i need an if else statement to tell it to differentiate between AM or Pm

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Re: How do I write a C++ program that converts from 24-hour notation to 12-hour notation?

Click to Expand / Collapse Quote originally posted by rock9449 ...

using an if else statement but what function i call i can put it in words but that's where i have a hard problem putting it into code
i know it would be something like
if hours < 12
pm = 12- hours ?
cout>>pm?

C++ Syntax (Toggle Plain Text)
if( hours < 12)
{
    pm = 'A';
}
else
{
    hours -= 12;
    pm = 'P';
}
if( hours < 12)
{
    pm = 'A';
}
else
{
    hours -= 12;
    pm = 'P';
}

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