Program exits after user input after my switch case

Question

I've been working on an assignment and after writing my code and running it I have noticed that my program exits after my inputting my first user input after my switch case.

I have asked around and found out that is was due to memory allocation on my struct/pointer and have tried initializing new on my int main but it still exits without running the whole program. I am a complete beginner on this and would ask for help.

My code is posted below, any help is appreciated, thanks a lot!

This is my declaration of struct & global variables as well as the function where my program exits

//struct declaration

struct Students {
    std::string givenName, lastName;
    int         studentType, NumSize, labUnits, lecUnits, totalUnits;
    char        paymentMode;
    long long   courseCode;
};
    
    //Students studs[100]; //global struct declaration
    
    //function prototype
    void
    infoStudent();
    
    void
    studentCode();
    
    void
    computation();
    
    //global variables
    bool inputerror;
    Students stud1;
    Students* studP;
    
    
   
void
infoStudent() {
    
    studP = new Students[size];   //allocates memory 
    delete [] studP;

    std::cout << "\nInput data for Student #" << ctr << ": " << std::endl;

    std::cout << "Student's Last Name: ";
    getline( std::cin, studP[ctr].lastName );

    std::cout << "Student's Given Name: ";
    getline( std::cin, studP[ctr].givenName );

    do {
        std::cout << "Student Number: ";
        std::cin >> studP[ctr].courseCode;
        inputerror = std::cin.fail();

        if ( inputerror || ( studP[ctr].courseCode < 2000000000 || studP[ctr].courseCode > 2999999999 ) ) {
            std::cout << std::endl << "Please enter a proper Student Number." << std::endl << std::endl;
            std::cin.clear();
            std::cin.ignore( 5, '\n' );
        }
    } while ( inputerror || ( studP[ctr].courseCode < 2000000000 || studP[ctr].courseCode > 2999999999 ) );

    do {
        do {
            std::cout << "Number of Laboratory Units: ";
            std::cin >> studP[ctr].labUnits;
            inputerror = std::cin.fail();

            if ( inputerror || ( studP[ctr].labUnits < 0 || studP[ctr].labUnits > 15 ) ) {
                std::cout << std::endl << "Please enter a proper amount of Laboratory Units." << std::endl << std::endl;
                std::cin.clear();
                std::cin.ignore( 5, '\n' );
            }
        } while ( inputerror || ( studP[ctr].labUnits < 0 || studP[ctr].labUnits > 15 ) );

        do {
            std::cout << "Number of Lecture Units: ";
            std::cin >> studP[ctr].lecUnits;
            inputerror = std::cin.fail();

            if ( inputerror || ( studP[ctr].lecUnits < 0 || studP[ctr].lecUnits > 15 ) ) {
                std::cout << std::endl << "Please enter a proper amount of Lecture Units." << std::endl << std::endl;
                std::cin.clear();
                std::cin.ignore( 5, '\n' );
            }
        } while ( inputerror || ( studP[ctr].lecUnits < 0 || studP[ctr].lecUnits > 15 ) );

        studP[ctr].totalUnits = studP[ctr].labUnits + studP[ctr].lecUnits;

        if ( studP[ctr].totalUnits <= 15 ) {
            std::cout << std::endl << "You have " << studP[ctr].totalUnits << " Total Units.\n";
        } else if ( studP[ctr].totalUnits > 15 ) {
            std::cout << std::endl
                      << "Please enter a proper amount of Laboratory and Lecture Units.\n(Must not exceed over 15 units.)\n"
                      << std::endl;
        }
    } while ( studP[ctr].totalUnits > 15 );

    do {
        std::cout << std::endl << "Mode of Payment ([F/f] Full or [I/i] Installment): ";
        std::cin >> (studP[ctr].paymentMode );;
        studP[ctr].paymentMode = std::tolower( studP[ctr].paymentMode );

        if ( studP[ctr].paymentMode == 'f' ) {
            std::cout << "Your chosen Mode of Payment is Full" << std::endl;
        } else if ( studP[ctr].paymentMode == 'i' ) {
            std::cout << "Your chosen Mode of Payment is Installment" << std::endl;
        }

        if ( studP[ctr].paymentMode != 'f' && studP[ctr].paymentMode != 'i' ) {
            std::cout << std::endl << "Please enter a proper mode of payment." << std::endl;
        }

    } while ( studP[ctr].paymentMode != 'f' && studP[ctr].paymentMode != 'i' );
}

Answer 1

You are allocating studP and then you immediately free the memory. After that you have a dangling pointer and then you are using this invalid pointer (all in function infoStudent ).

I have to mention that you have a switch-case and you call the same function with no arguments in every case, so this is pointless.

I should also mention, that you have several magic numbers in your code and you shouldn't use global variables that way. Also be sure to initialize all variables.