c++ - boolean statement to change 24 hour format to 12 hour format for time equations in a switch menu? -

so have project requires me make clock/watch. default format of code 24 hour format option 5 in menu, "toggle 24 hour format", required hour formats change 12 hour format. not required keep previous input of 24 hours, example: user inputs 23:45, presses option 5, option 4, shouldn't display 11:45pm. user should go option 1 input new time , input 'a' choose or 'p' choose pm. question is, how write boolean statement when user inputs '5' in switch, void functions know format 12 hour format , variation of equations deal 12 hour times.

the problem see happening subtraction or addition functions in 12 hour format. how write 12 hour addition , subtraction statements if time 12:30 , 45 minutes added, new time gets outputted 1:15 , not 13:15.

i have idea of how (i'm terrible boolean logic , functions):

bool mode     if (mode==true)     {         \\12 hour format     }     else (mode==false)     {         \\24 hour format     } 

but have no idea how format , make option 5 changes mode. kind of understand how in void functions:

if mode==true then add hours , minutes 12 hour format

but again, confused on how this. looked @ similar problem posted 6 days ago, answer didn't satisfy me, , dealt single input , made user has input 24 or 12 denote time instead of making option 5 toggles mode. did use:

mode= !mode 

which looked promising if option 5 toggled, user can input option 5 again , make format toggle again, again: how make option 5 toggles mode?

#include <iostream> #include <iomanip> #include <sstream>  using namespace std;  void calcdeltafutr(int h, int m, int deltah, int deltam, int& hnew, int& mnew); void calcdeltapast(int h, int m, int deltah, int deltam, int& hnew, int& mnew); void gettime(int &h, int &m, bool mode); void rolltimeforward(int& h, int& m); void rolltimeback(int& h, int& m); void printtime(int h, int m, bool mode);  void calcdeltafutr(int h, int m, int deltah, int deltam, int& hnew, int& mnew) {     cout << "enter new time:" << endl << "hours: ";     cin >> deltah;     cout << "minutes: ";     cin >> deltam;     hnew = h + deltah;     mnew = m + deltam;     rolltimeforward(hnew, mnew);     cout << "the new time is: " << hnew << ":" << mnew << endl;     return; } void calcdeltapast(int h, int m, int deltah, int deltam, int& hnew, int& mnew) {     cout << "enter new time:" << endl << "hours: ";     cin >> deltah;     cout << "minutes: ";     cin >> deltam;     hnew = h - deltah;     mnew = m - deltam;     rolltimeback(hnew, mnew);     cout << "the new time is: " << hnew << ":" << mnew << endl;     return; } void gettime(int &h, int &m, bool mode) {     cout << "enter time (hours, minutes): ";     cin >> h;     cin >> m;     if (h>23 || m>59 || h<0 || m<0)     {         cout << "invalid input! please input value hours below 24 , value of minutes below 60." << endl;     }     return;  } void rolltimeforward(int& h, int& m) {     h = h + m / 60;     m = m % 60;     h = h % 24;     return; } void rolltimeback(int& h, int& m) {     h = h - m / 60;     m = m % 60;     return; } void printtime(int h, int m, bool mode) {     cout << "the current time is: ";     cout << h << ":" << m << endl;    } int h, m, deltah, deltam, hnew, mnew; bool mode; char time;  int main() {     int choice;         {         cout << "-----menu-----" << endl << endl << "1-enter time" << endl << "2-add delta time" << endl << "3-subtract delta time" << endl << "4-display current time" << endl << "5-toggle 24 hour mode" << endl << "6-exit" << endl;         cin >> choice;          switch (choice)         {         case 1:             gettime(h, m, mode);             continue;         case 2:             calcdeltafutr(h, m, deltah, deltam, hnew, mnew);             continue;         case 3:             calcdeltapast(h, m, deltah, deltam, hnew, mnew);             continue;         case 4:             printtime(h, m, mode);             continue;         case 5:             cout << "12 hour mode turned on" << endl;             continue;         case 6:             cout << "exiting...";             break;         }         if (choice != 1 && choice != 2 && choice != 3 && choice != 4 && choice != 5 && choice != 6)         {             cout << "invalid input! please try again!" << endl << endl;         }         else         {             break;         }     } while (choice != 6);       return 0; } 

your print time function doesn't mode.

void printtime (int h, int m, bool mode) {   if (mode) // assuming when mode true means 24 hour time   {     //print time in 24 hour format   }   else   {     //print time in 12 hour format    } } 

also time needs similar because of now, can set using 24 hour format.

in switch statement case 5, want switch mode value. mode = !mode work long mode has boolean value assigned it.

side note: need function prototypes if function called before defined.