Thread: Typedef and Struct

Hi, I am doing a little work and I have this.

Code:

#include <stdio.h>
#include <stdbool.h>

#define NumberOfStudents 10

struct Student
{
	int studentID;
	float balanceOwed;
	float gpa;
};

typedef struct Student student;

int main( int argc, char **argv )
{
	int	i;
	int	id;
	int	index = -1;	
	bool	willGraduate = true;

	Student student[]={
            {10, 0.0, 1.0},
            {20, 100.0, 3.0},
	    {30, 0.0, 3.5},
	    {40, -25.0, 3.25},
	    {50, 0.0, 3.75},
	    {60, 1000.0, 1.5},
	    {70, 0.0, 3.25},
	    {80, -50.0, 3.0},
	    {90, 0.0, 3.9},
	    {100, 1.0, 4.0}
	}

	
	printf( "Enter student ID: " );
	scanf( " %d", &id );

	
	for( i = 0; i < NumberOfStudents; i++ )
	{
		if( id == student[i].studentID )
		{
			break;
		}
	}

	
	if( i >= 0 )	
	{
		
		if( student[i].balanceOwed > 0.0 )
		{
			willGraduate = false;
			printf( "  Student owes ($%0.2f)\n",
					student[i].balanceOwed );
		}

		
		if( student[i].gpa < 2.0 )
		{
			willGraduate = false;
			printf( "  This student has a low GPA (%.2f)\n", student[i].gpa );
		}

		
		if( willGraduate )
			printf( "  This student WILL graduate\n" );
		else
			printf( "  and will NOT graduate\n" );
	}
	else	
		printf( "  Sorry, student ID (%d) not found\n", id );

	return( 0 );
}

Gives error here -->Student student[]={ of

'Student' undeclared (first use in this function).
(Each undeclared identifier is reported only once for each function it appears in.)
syntax error before "student".

Where have gone wrong?
thanks

maybe in your typedef it should read

typedef struct student student;

its thinking "Student" and "student" are different. either caps or no caps


(I think. I'm new at this but I would try starting with that.)

Originally Posted by swoopy

Either:

Code:

	student student[]={

Or you could also use:

Code:

	struct Student student[]={

Naming a variable the same name as a struct tag, while allowed, is not usually a good thing.

Originally Posted by dwks

Why not? You don't have to remember two names.

I don't mean you shouldn't name the typedef the same as the struct tag. I do that all the time. I mean, don't declare a VARIABLE which has the same name as the struct tag (or typedef). In the example:

Code:

student student[10];

It's the repetition of "student", once as a typename, once as an identifier, that I dislike.

EDIT: For one thing, it completely hoses cscope. You say, "search for definition" for "student" -- will it give you the variable definition, or the struct definition? Who the hell knows. Ran into this just the other day, even. Basic idea:

Code:

struct foo { ... };
typedef struct foo foo;
static foo foo;

Where foo is a struct tag, a typename, AND a variable all in the same file. The first two are okay, it's that third line that bugs me.

cj147 I appreciate that;

dwks as always you teach;

swoopy, brewbuck you both pointed out good programming practices for me.

All bear with me, I am learning and I will do my best to incorporate everything.

Thanks to all for being so fast with the replies!!!

Originally Posted by swoopy

Well if one's capitalized, and the other isn't, I don't see why not. Unless you're coding in a language where case doesn't matter.

If case matters, then the two aren't the same any more and I won't complain. As much. My personal naming style forbids use of upper case altogether except in macros, so that can't happen.

(That's PERSONAL style. What I do at work is totally different.)