compute the earnings per shift of security guard

Output1--

Input starting hours: 7
Input starting minutes: 0
Input ending hours: 2
Input ending minutes: 0

Total charge: 115
Total hours of work: 7

Output 2--

Input starting hours: 9
Input starting minutes: 0
Input ending hours: 5
Input ending minutes: 30

Total charge: 155
Total hours of work: 8.5

CPP/ShiftEarning.cpp

@@ -0,0 +1,80 @@
+//using c++ and please explain to me the calculation.
+//Write a program that computes the earnings per shift for a security guard. A security guard charges $15 per hour before midnight and $20 after midnight. The program reads the starting time in hours and minutes and the ending time in hours and minutes. All times are between 6:00 pm, and 5:59 am, using a 12-hour clock. For example, you should consider hour 8 as 8 pm and hour 2 as 2am.
+//The program should check the validity of the inputs as follows.
+//1) Hours are from 0-11 (0 for midnight).
+//2) Minutes are from 0-59.
+//3) The start time must be before midnight.
+//4) The end time must be after the start time.
+//The program should display specific warnings regarding the above when the user submits invalid input; the program should prompt the user to re-enter the times again. The program should output the total hours worked and the total earnings per shift.
+//Example: >7h 0m to 2h 0m You have worked 7 hours in this shift, earning $115.
+
+#include <iostream> // standard input and output library
+using namespace std;
+//main function
+int main(){
+ int hour, mints, endhour, endmints; //taking user input from user about shift time
+ cout<<"Input starting hours: ";
+ cin>> hour;
+ cout<<"Input starting minutes: ";
+ cin>> mints;
+
+ cout<<"\nInput ending hours: ";
+ cin>> endhour;
+ cout<<"Input ending minutes: ";
+ cin>> endmints;
+
+ int hourpm, houram, mintspm, mintsam;
+ //hours
+ //calculating number of hours of shift before midnight
+ if(hour>=6 && hour<12){
+ if(mints>0){
+ hourpm = 12 - (hour+1);
+ }
+ else{
+ hourpm = 12-hour;
+ } 
+ }
+ else{
+ cout<<"Input correct time";
+ }
+ //calculating number of hours of shift after midnight
+ if(endhour>=0 && endhour<6){
+ houram = endhour-0;
+ }
+ else{
+ cout<<"Input correct time";
+ }
+
+ //minutes
+ //calculating number of minutes of shift before midnight
+ if(mints>0 && mints<60){
+ mintspm= 60-mints;
+ }
+ else{
+ mintspm=mints;
+ }
+ //calculating number of minutes of shift after midnight
+ if(endmints>0 && endmints<60){
+ mintsam= endmints-0;
+ }
+
+ // converting minutes into hours
+ float mintoHourAM, mintoHourPM;
+ mintoHourPM = (float)mintspm/60;
+ mintoHourAM = (float)mintsam/60;
+
+ // calculating shift charge before midnight and after midnight separately
+ float chargeAM, chargePM, totalCharge;
+ chargePM = ((float)hourpm + mintoHourPM) * 15;
+ chargeAM = ((float)houram + mintoHourAM) * 20;
+
+ // calculating total shift charge
+ totalCharge = chargePM + chargeAM;
+ cout<<"\nTotal charge: "<<totalCharge;
+
+ // calculating total shift hour
+ float totalhours;
+ totalhours = hourpm + mintoHourPM + houram + mintoHourAM;
+ cout<<"\nTotal hours of work: "<<totalhours;
+
+}