Question

in C++

Write a program that converts a time in 12-hour format to 24-hour format. The program will prompt the user to enter a time in HH:MM:SS AM/PM form. (The time must be entered exactly in this format all on one line.) It will then convert the time to 24 hour form. You may use a string type to read in the entire time at once including the space or you may choose to use separate variables for the hours, minutes, seconds and AM/PM.

Run your program and show the output for each of the five examples below.

Examples:

Input (12HR) Output(24hr)

5:30:00 PM 17:30:00
6:45:50 AM 06:45:50
12:32:30 AM 00:32:30
12:15:18 PM 12:15:18
1:02:22 PM 13:02:22

Answer 1

#include<iostream>
using namespace std;

//function to convert 12 hours format to 24 hours format
void format12HoursTo24Hours(string str)
{
//if time is in AM
   if ((str[9] == 'A') || (str[8] == 'A'))
   {
       for (int i=0; i <= 7; i++)
       {
           cout << str[i];
       }
   }
   //if time is in PM
   else
   {
   int hh;
   if(((int)str[1] - '0') >=0 && ((int)str[1] - '0') <=9)
   {
   hh = (((int)str[0] - '0') * 10 + ((int)str[1] - '0'));
   }
   else
   {
   hh = ((int)str[0] - '0');
   }
  
       if (hh == 12)
       {
           for (int i=0; i <= 7; i++)
               cout << str[i];
       }
       else
       {
           hh = hh + 12;
           cout << hh;
           if(str[2]!=':')
           cout<<":";
           for (int i=2; i <= 7; i++)
               cout << str[i];
       }
   }
}

int main()
{
//string variable declartion
string timeStr;
  
//display message
cout<<"Enter time in HH:MM:SS AM/PM format: ";
cin>>timeStr;
  
cout<<endl<<"The time in 24 hours format is: ";
  
//function calling
format12HoursTo24Hours(timeStr);
return 0;
}

OUTPUT: