error C2064: term does not evaluate to a function taking 2 arguments

[misterMatt]

Hey guys, I'm trying to create a little program here, but I'm having some trouble with it.

I'm getting the following error message: error C2064: term does not evaluate to a function taking 2 arguments. I don't really kn ow what the hell that means, would someone mind pointing out what the problem is so I can fix it? I was under the impression that a function as an argument was perfectly cool to do. Anyway, here are the two offensive lines, followed by the function definitions.

 
//bad lines
x += delta_x((velocity_x(user_velocity, DEGREES)), t);
y -= delta_y((velocity_y(user_velocity, DEGREES)), t);

//function definitions: 
double velocity_x(int vel, int degrees){
	return vel * cos(degrees * 3.141592654/180.0);
}
double velocity_y(int vel, int degrees){
	return vel * sin(degrees * 3.141592654/180.0);
}


double delta_x(double vel_x, double time){
	return vel_x * time;
}
double delta_y(double vel_y, double time){
	return vel_y * time - (.5 * (9.8 * (time*time)));
}

Any help would be greatly appreciated, because I have no idea what is wrong.

[tabstop]

Do you have prototypes for your functions?

[misterMatt]

yes I do, at the top of my file:

double velocity_x(int vel, int degrees);
double velocity_y(int vel, int degrees);
double delta_x(double vel_x, double time);
double delta_y(double vel_y, double time);

[tabstop]

Good. Then you're not getting that error. (No really. I just compiled it, and you're not getting any error at all.)

[misterMatt]

I'm confused. It still fails compilation for me.

[tabstop]

It shouldn't make a difference, but remove the superfluous parentheses around the function calls and see if that helps. After that, I don't know. I'm using VS2008; I don't know what version you have, but you may need to yell.

[laserlight]

I'm confused. It still fails compilation for me.

Provide the smallest and simplest complete program that demonstrates the error.

[Salem]

x += delta_x((velocity_x(user_velocity, DEGREES)), t);
y -= delta_y((velocity_y(user_velocity, DEGREES)), t);
You've got local variables with the same names in whatever function you've got this code in.

One way out

x += delta_x((::velocity_x(user_velocity, DEGREES)), t);
y -= delta_y((::velocity_y(user_velocity, DEGREES)), t);

[Elysia]

It's better to rename the functions (and/or the variables) to something different.

[master5001]

Off topic...

#include <math.h>

double velocity_x(int vel, int degrees){
	return vel * cos(degrees * M_PI/180.0);
}
double velocity_y(int vel, int degrees){
	return vel * sin(degrees * M_PI/180.0);
}