Kind a beginner thingie...

[Zvonko]

Hi

For about an hour now I'm trying to get with my head through the wall, but I can't.. ;o)
I really can't figure out what't the problem with my program. It's something with variables and &-operator, but what...
Can someone please look at it?

#include <stdio.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>

void getFunctionParameters(void);
void sqeq(double a, double b, double c, double &x1r, double &x1i, double &x2r, double &x2i);
//void sqeq(double &a, double &b, double &c, double &x1r, double &x1i, double &x2r, double &x2i);
//void sqeq(double a, double b, double c, double x1r, double x1i, double x2r, double x2i);

double paramA, paramB, paramC;

int main(int argc, char* argv[]) {
	double X1r = 0, X1i = 0, X2r = 0, X2i = 0;
	
	if (argc == 1) 
		getFunctionParameters();
	else {
		printf("\n/--------------------------------------------------\\\n");
		printf("| Program za izracun vrednosti kvadratne funkcije. |\n");
		printf("|                                                  |\n");
		printf("| (C) 2002 by Tanja Vasilevska                     |\n");
		printf("\\--------------------------------------------------/\n");
		exit(0);
	}
	
	sqeq(paramA, paramB,paramC, X1r, X1i, X2r, X2i);

	printf("Rezultat:\n");
	if (X1i == 0 && X2i == 0) {
		printf("\tX1 = %f\n", X1r);
		printf("\tX2 = %f\n", X2r);
	}
	else {
		printf("\tRe(X1) = %f; Im(X1) = %f\n", X1r, X1i);
		printf("\tRe(X2) = %f; Im(X2) = %f\n", X2r, X2i);
	}

	return 0;
}


void getFunctionParameters(){
	char pravilen = ' ';
	float A, B, C;

	printf("----------------------------------------------\n");
	printf("Vpiši vrednost parametra A: ");
	scanf("%f", &A);
	printf("Vpiši vrednost parametra B: ");
	scanf("%f", &B);
	printf("Vpiši vrednost parametra B: ");
	scanf("%f", &C);
	printf("----------------------------------------------\n");
	printf("Funkcija: 0 = %fx^2 + %fx + %f\n", A, B, C);
	printf("----------------------------------------------\n");
	
	paramA = (double)A;
	paramB = (double)B;
	paramC = (double)C;
}


void sqeq(double a, double b, double c, double &x1r, double &x1i, double &x2r, double &x2i) {
	double d = b * b - 4 * a * c;

	if (d >= 0) {
		x1r = (-b + sqrt(d)) / (2 * a);
		x2r = (-b - sqrt(d)) / (2 * a);
		x1i = 0;
		x2i = 0;
	}
	else {
	    x1r = -b / (2 * a);
		x2r = -b / (2 * a);
		x1i = sqrt(-d) / (2 * a);
		x2i = -x1i;
    }
}

And errors that I get with VC++ 6:

--------------------Configuration: main - Win32 Debug--------------------
Compiling...
main.c
C:\Homecooked\Tanja\main.c(7) : error C2143: syntax error : missing ')' before '&'
C:\Homecooked\Tanja\main.c(7) : error C2143: syntax error : missing '{' before '&'
C:\Homecooked\Tanja\main.c(7) : error C2059: syntax error : '&'
C:\Homecooked\Tanja\main.c(7) : error C2059: syntax error : ')'
C:\Homecooked\Tanja\main.c(27) : warning C4013: 'sqeq' undefined; assuming extern returning int
C:\Homecooked\Tanja\main.c(64) : error C2143: syntax error : missing ')' before '&'
C:\Homecooked\Tanja\main.c(64) : error C2143: syntax error : missing '{' before '&'
C:\Homecooked\Tanja\main.c(64) : error C2059: syntax error : '&'
C:\Homecooked\Tanja\main.c(64) : error C2059: syntax error : ')'
Error executing cl.exe.

main.exe - 8 error(s), 1 warning(s)

Thanks

[parksie]

C doesn't have references - you can't use:

void func(int &ref) {
    ref += 1;
}

...you'd have to use:

void func(int *ptr) {
    *ptr += 1;
}

[Zvonko]

Huh... ;o)

So I have to change all & to *. Am I right?
I already tried that but somehow didn't work properly - i got standard windows error: "The program made illegal funcion call in module ... ". I'll try it again - it may work.
Thanks

Zvonko

[parksie]

You do in the function prototypes, then when you pass the variables to the function, use & in front of it (to emphasise passing the address). Then in the function, use * to dereference the pointer to get a variable you can change.

[Zvonko]

Thanks.

I did that and it worked.
You see, we were learning C in school but I kind a forgot that arithmetics with pointers... I hate pointers...