Thread: Passing string through a function...

Howdy. I have been pondering how I would go about taking, in this case, the name of a subject (for a GPA tracking program), and pass it through to an overloaded constructor. I figured pointers were the solution, but nonetheless I kept getting "int to char[11]" errors and the like. Here is a stubbed out version of what I've attempted so far:

#include <iostream.h>

class Course
{

public:

Course();
Course(int pname, float credits, unsigned short sem, unsigned short per);
~Course();

private:

char courseName[11];
float creditsAtt;
unsigned short Semesters;
unsigned short Period;

};

Course::Course()
{

}

Course::Course(int pname, float credits, unsigned short sem, unsigned short per)
{

courseName = * pname; // so this should give the string,
// and courseName is a string
// identical to the local string
// in int main(). Where have I
// fouled things up?
creditsAtt = credits;
Semesters = sem;
Period = per;

}

//////////////////////////////////////////////////
//////////////////////////////////////////////////

int main()
{

char name[11];
float credits = 0;
unsigned short sem = 0;
unsigned short per = 0;

// ( I deleted a lot of explanation, irrelevant stuff here )

//////////////////////////////////////////////////
//////////////////////////////////////////////////

Course * All = new Course[9];
Course * pCourse;

int * pname = 0; // OK, setting a pointer for each string

for(short p = 0; p < 9; p++)
{

cout << "\nPlease enter the name of period number " << p << ", 10 characters max please:\t";

cin.get(name, 10);

pname = &name; // OK. So this sets the pointer to name's
// address, right?

// ( deleted more irrelevant stuff, questions for info )

pCourse = new Course(pname, credits, sem, per); // OK, so
// this should set name's address at pname into the parameter?
All[p] = * pCourse;
delete pCourse;
delete pname; // do I have to do this in this case?

}

delete [] All;

return 0;

}

////////////////////////////////////////////////////////
////////////////////////////////////////////////////////

END OF CODE

Hey, thanks a billion. Just wondered if anyone could give this a quick scan and detect my obvious error. :-P

pname should be char *pname in your main and constructor. Also, use <iostream>, not <iostream.h>

Course(int pname, float credits, unsigned short sem, unsigned short per)

In your parameter list you are saying pname is of type int. If you declare a parameter to be

int Mr_Compiler_this_is_a_pointer

the compiler won't change the type to int*. Similarly, just because you use the name "pname" as your parameter name doesn't mean it's a pointer.

Oh okay thanks guys, but I've noticed two snags: when I change it to <iostream>, I get like 33 errors and 3 warnings, saying that basically everything is done incorrectly. also, for some reason when i changed the pointers to char and added pointer designations in main and the constructor, nothing changed.

Course::Course(char *pname, float credits, unsigned short sem, unsigned short per)
{

courseName = *pname; // right here. the error code is:


char courseName[11];

Arrays names act like pointers but they aren't exactly pointers. I cannot explain the internals of why you can't do this:

char text[10];
text= "dog";

but basically it's like a type mismatch "dog" is a string literal that's length is 4(when it's stored in memory a \0 is appended), and text's length is 10. They have to be equal.

The following code demonstrates that a true pointer can point to cstyle strings of different lengths:

char* pname;
pname = "dog";
pname = "A bigger dog";

)