Total newbie problem.. corrupted stack around variable

I've spent a long, long time trying to figure out what I'm doing wrong, and I still can't find it. I'm not used to Visual Studio's Debugger, and I hope you all won't mind me asking for help. I'm getting a stack around variable error, which I know is when something tries to write out of bounds. Anyway, here's the code (my first attempt at a C++ class)

Code:

---

#include <iostream>
#include <string>

using namespace std;

class Studentgrade
{
private:
        char student[24];
        int quizzes[4];

public:
        void askName()
{
        cout << "Please enter the student's name: ";
                cin.getline(student, 24);
                quizzes[0] = 0;
                quizzes[1] = 0;
                quizzes[2] = 0;
                quizzes[3] = 0;
}

        void setGrade(int sc, int x)
{
        if(x>=0 && x<4)
        {
                quizzes[x] = sc;
        }
}

        void getName(char name[]) const
{
        strcpy_s(name, strlen(name), student);
}

        float getAve() const
{
        int tot = 0;
        tot = (quizzes[0] + quizzes[1] + quizzes[2] + quizzes[3]);
        return (tot/static_cast<float>(4.0));
}
};

int main()
{
        Studentgrade sg;
        char student[24];
        sg.askName();
        sg.setGrade(100,0);
        sg.setGrade(90,1);
        sg.setGrade(100,5);
        sg.setGrade(100,3);
        sg.getName(student);
        cout << student << "'s quiz average is " << sg.getAve() << endl;
        return 0;
}

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If I debug with "john smith," the string never even makes it into the sg.student instance. I guess I don't understand how member functions are supposed to write to the instance rather than original class declaration (if that makes sense)

Sigh.

Oh... I guess this should be in "C++ Programming" and not "Visual C++."

Save yourself a great deal of time and trouble: Use std::strings rather than char arrays. You're already including the header for them anyway.

sg.setGrade(100,5);

you don't have fifth element in int quizzes[4];

should be:
sg.setGrade(100,2);

^Not the problem.

Quote:

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Originally Posted by Lindley

^Not the problem.

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Its not. Its bug.

void getName(char name[]) const

also have a problem/bug as you wish. You should pass parameter as reference.

Quote:

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Originally Posted by streamer

Its not. Its bug.

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Maybe; or maybe it's a test to make sure that the "if" statement within the function properly catches bad input.

Quote:

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void getName(char name[]) const

also have a problem/bug as you wish. You should pass parameter as reference.

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Reference passing is pretty much irrelevant in the case of arrays. If he were to substitute a std::string that would be true.

Quote:

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Originally Posted by Georgie Fruit

I've spent a long, long time trying to figure out what I'm doing wrong, and I still can't find it. I'm not used to Visual Studio's Debugger, and I hope you all won't mind me asking for help. I'm getting a stack around variable error, which I know is when something tries to write out of bounds. Anyway, here's the code (my first attempt at a C++ class)

Code:

---

void getName(char name[]) const
{
        strcpy_s(name, strlen(name), student); //are you sure?
}

---

If I debug with "john smith," the string never even makes it into the sg.student instance. I guess I don't understand how member functions are supposed to write to the instance rather than original class declaration (if that makes sense)

Sigh.

---

Well your askName() method works fine for me, are you sure it gives you a problem? Regardless, you ought to look again at the way you're using strcpy_s, particularly the way you're telling it how long the source string is, hmm? Also, in a little project like this it's a good idea to not give a local variable the same name as a member (as you have with student in main()), the compiler will cope perfectly well but it can confuse the human.

HTH

I believe GrimmRiffer is on the right track.

You're strcpy_s function is incorrect...the second parameter is the size of the DESTINATION buffer - in this case it should be 24.

By using

Code:

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strcpy_s(name, strlen(name), student);

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you're telling it that the buffer is only the same length as the name - which doesn't leave room for the terminating NULL character.

Hope that helps.