Help C++ 24 Hour alarm to 12 Hour

[cherrypie12]

#include <iostream>
#include <string>
#include <windows.h>
#include <stdlib.h>
#include <time.h>
#include <sstream>
using namespace std;
class alarm {
public:
tm alarmtime, presenttime, differenceintime;
time_t now;
alarm()
{
now = time(0);
presenttime = *localtime(&now);
alarmtime = presenttime;
alarmtime.tm_sec = 0;
}
void getTime()
{
string time;
cout<<"Enter Alarm Time in 24-hour format [HH:MM]: "; getline(cin,time);
int pos = 0, h;
while ((pos = time.find(':')) != string::npos)
{
string token = time.substr(0,pos);
stringstream convert (token);
convert >> alarmtime.tm_hour;
time.erase(0,pos+1);
}
stringstream convert (time);
convert >> alarmtime.tm_min;
}
void timeDifference()
{
int sec = difftime(mktime(&alarmtime),now);
differenceintime.tm_min = sec / 60;
differenceintime.tm_hour = differenceintime.tm_min / 60;
differenceintime.tm_min = differenceintime.tm_min % 60;
differenceintime.tm_sec = sec % 60;
if (sec < 0)
{
differenceintime.tm_hour = 24 + differenceintime.tm_hour - 1;
differenceintime.tm_min = 0 - differenceintime.tm_min;
differenceintime.tm_sec = 0 - differenceintime.tm_sec;
}
}
void start_alarm()
{ while (true)
{
system("cls");
now = time(0);
presenttime = *localtime(&now);
timeDifference();
cout<<"TIME REMAINING: "<<differenceintime.tm_hour<<":"<<differenceintime.tm_min<<":"<<differenceintime.tm_sec;
if (differenceintime.tm_hour == 0 && differenceintime.tm_min == 0 && differenceintime.tm_sec == 0)
{
cout<<endl<<"Time Ended"<<endl<<">>> Press CTRL+C or Close the window to stop the alarm <<<"<<endl;
break;
}
}
}
};
int main()
{
alarm a;
a.getTime();
a.start_alarm();
for (int i = 0; ; i = i + 50)
Beep(i,1000);
return 0;
}

 

[Misanthropy]

gagawing 12hr?

 

[cherrypie12]

opo

 

[Misanthropy]

differenceintime.tm_hour = 12 + differenceintime.tm_hour - 1;

this i guess

pero gagawa ka pa function para sa AM at PM Meridian

syempre pag ginawa mong 12hr clock, kelangan maidentify yung Meridian para malaman kung Gabi ba o umaga