Thread: Console stops working when program is running.

Since I am not getting any error I can't find what is wrong with the program.
The text of the exercise is:
"Create a class named StudentGrade. Include fields for a student ID number, studentname (use the Person class from Exercise 3), numeric test score, possible points, andletter grade.
Create a constructor that requires the student ID, name, and test score, and allows a fourth parameter that holds possible test points. If a value for possible points isnot passed to the constructor, the possible points value defaults to 100. (If a 0 value ispassed for possible points, force possible points to 1 so that you do not divide by 0 whencalculating a grade.)
The constructor calculates the student’s percentage (divides scoreby possible points) and assigns a letter grade based on: 90% and above (A), 80% (B), 70%(C), and 60% (D). Create a main()function that instantiates and displays enoughStudentGrade objects to test a variety of scores and possible point values"

Code:

#include <iostream>
using namespace std;


class Person
{
    private:
        string lastName;
        string firstName;
        string zipCode;
    public:
        Person();
        Person(string , string , string);
        string getLastName();
        string getFirstName();
        string getZipCode();
        void setFirstName(string);
        void setLastName(string);
            
};
Person::Person()
{
    lastName = firstName = zipCode = "X";
    
}
Person::Person(string lName, string fName, string zCode)
{
    lastName = lName;
    firstName = fName;
    zipCode = zCode;
}
string Person::getLastName()
{
    return lastName;
}
string Person::getFirstName()
{
    return firstName;
}
string Person::getZipCode()
{
    return zipCode;
}
void Person::setFirstName(string firstName)
{
    this->firstName = firstName;
}
void Person::setLastName(string lastName)
{
    this->lastName = lastName;
}


class StudentGrade
{
    private:
        int idNum;
        int testScore;
        int possiblePoints;
        char letterGrade;
        Person Student;
    public:
        StudentGrade(int , string, int, int = 100);
        char getLetterGrade();
};
StudentGrade::StudentGrade(int idNum, string firstName, int testScore, int possiblePoints)
{
    Student.setFirstName(firstName);
    this->idNum = idNum;
    if(possiblePoints = 0)
        possiblePoints = 1;
    if(testScore/possiblePoints >= 90)
        letterGrade = 'A';
    if(testScore/possiblePoints >= 80)
        letterGrade = 'B';
    if(testScore/possiblePoints >= 70)
        letterGrade = 'C';
    if(testScore/possiblePoints >= 60)
        letterGrade = 'D';
    
}
char StudentGrade::getLetterGrade()
{    
    return letterGrade;
}
int main()
{
    StudentGrade NI(21, "Nikola" , 63 , 100);
    cout << NI.getLetterGrade();
    return 0;
}

While your program may not have any errors it does have several warnings you should fix:

|=== Build: Debug in testcpp (compiler: gcc 6.1.0) ===|
main.cpp||In member function ‘void Person::setFirstName(std::__cxx11::string)’:|
main.cpp|44|warning: declaration of ‘firstName’ shadows a member of ‘Person’ [-Wshadow]|
main.cpp|9|note: shadowed declaration is here|
main.cpp||In member function ‘void Person::setLastName(std::__cxx11::string)’:|
main.cpp|48|warning: declaration of ‘lastName’ shadows a member of ‘Person’ [-Wshadow]|
main.cpp|8|note: shadowed declaration is here|
main.cpp||In constructor ‘StudentGrade::StudentGrade(int, std::__cxx11::string, int, int)’:|
main.cpp|66|warning: declaration of ‘possiblePoints’ shadows a member of ‘StudentGrade’ [-Wshadow]|
main.cpp|59|note: shadowed declaration is here|
main.cpp|66|warning: declaration of ‘testScore’ shadows a member of ‘StudentGrade’ [-Wshadow]|
main.cpp|58|note: shadowed declaration is here|
main.cpp|66|warning: declaration of ‘idNum’ shadows a member of ‘StudentGrade’ [-Wshadow]|
main.cpp|57|note: shadowed declaration is here|
main.cpp|70|warning: suggest parentheses around assignment used as truth value [-Wparentheses]|

Next do you have a question or problem with this code? You really need to ask specific questions and thoroughly describe the problem.


Jim

Is just a pointer to the address in memory where each type is stored.

In the content shown

Code:

this->firstName = firstName;

the this-> tells the compiler to use the member variable with the name of firstName.

The warning is because the parameter has the same name as a member variable which is usually a bad idea because it hides the member variable with the same name. Even though the program is correct because the OP properly scoped the member variable, naming parameters the same as your member variables is considered a bad habit. I really recommend you stop naming your parameters the same as your member variables.

Also when you're dealing with non-POD types like std::string IMO it would be better to pass the parameter by reference/const reference into your functions, to avoid the unnecessary and possibly costly copy operation.

Code:

void Person::setFirstName(const std::string& first_name)
{
    firstName = first_name;
}

about the assignment

By the way this function is setting the first name to a new value supplied by the parameter, not initializing the variable as in the constructor.

I have a problem that the console just crashes when I compile and run the program , I don't get any error like you did in your compiler, so I don't understand what is wrong with the program.

Then you need to see about increasing your compiler warning level. Your compiler should be able to warn you about the problems with your code. And note that the reason your program is crashing is because you are dividing by zero because of the problem pointed out by the last warning (main.cpp|70|warning: suggest parentheses around assignment used as truth value [-Wparentheses]| ). Also you may want to start compiling your program, without running, so you can see any and all warning messages. Remember just because the program compiles doesn't mean that it is warning free and warning should always be fixed, never ignore warnings.

Jim

Originally Posted by jimblumberg

In the content shown

Code:

this->firstName = firstName;

the this-> tells the compiler to use the member variable with the name of firstName.

The warning is because the parameter has the same name as a member variable which is usually a bad idea because it hides the member variable with the same name. Even though the program is correct because the OP properly scoped the member variable, naming parameters the same as your member variables is considered a bad habit. I really recommend you stop naming your parameters the same as your member variables.

Also when you're dealing with non-POD types like std::string IMO it would be better to pass the parameter by reference/const reference into your functions, to avoid the unnecessary and possibly costly copy operation.

Code:

void Person::setFirstName(const std::string& first_name)
{
    firstName = first_name;
}

about the assignment

By the way this function is setting the first name to a new value supplied by the parameter, not initializing the variable as in the constructor.


Then you need to see about increasing your compiler warning level. Your compiler should be able to warn you about the problems with your code. And note that the reason your program is crashing is because you are dividing by zero because of the problem pointed out by the last warning (main.cpp|70|warning: suggest parentheses around assignment used as truth value [-Wparentheses]| ). Also you may want to start compiling your program, without running, so you can see any and all warning messages. Remember just because the program compiles doesn't mean that it is warning free and warning should always be fixed, never ignore warnings.

Jim

Thank you.