Not sure how to use functions and pass arguments

[anton478]

I am having a hard time passing arguments. The function fallingDistance is supposed to acquire a value for the variable time from the function seconds from 1-10 seconds. Function main is supposed to call function seconds 10 times. However the output of my program is "The distance is 0" ten times it does not do the calculations I want it to. What am I doing wrong?

#include <iostream>
#include <cmath>
#include <iomanip>
using namespace std;

//Prototypes
void seconds();
void fallingDistance (int time, double gravity = 9.8);

int main ()
{
       for (int count = 1; count <= 10; count++)
	seconds();

	system ("pause");
	return 0;
}

void seconds()
{
	static int value = 1;
	fallingDistance(value);
	value++;
}

void fallingDistance(int time, double gravity)
{

	double distance;
	distance = (1/2) * gravity * pow(time, 2.0);
	cout << "The distance is " << distance << endl;

}

[TheIdeasMan]

Hi anton,

First up, please always use code tags:

http://www.cplusplus.com/articles/z13hAqkS/

Your problem is with this line:

distance = (1/2) * gravity * pow(time, 2.0);

The (1/2) does integer division and evaluates to 0. If you want FP arithmetic write (1.0/2.0)

Also, the pow function is very expensive for squaring numbers (it uses a series to calc the answer) , so just do (time * time) . Only use the pow function when the second arg isn't a whole number, as in pow(time, 1.2) , say.

You probably don't need 2 functions for this, can you figure out how to do it with 1 function.

A final point, avoid using magic numbers like 10 and 9.8 in your code - prefer to make them const variables, then refer to them by the variable name:

const unsigned int MaxTime = 10;
const double Gravity = 9.8;


for (int Time =  1; Time < MaxTime + 1; ++Time) { // always use braces even if 1 statement
    FallingDistance(Time, Gravity);
}

Good Luck

[AbstractionAnon]

distance = (1/2) * gravity * pow(time, 2.0);

(1/2) is an integer expression, which will always be zero. It doesn't matter what the rest of the expression is, the result will always be zero.

PLEASE USE CODE TAGS (the <> formatting button) when posting code.
http://v2.cplusplus.com/articles/jEywvCM9/
It makes it easier to read your code and it also makes it easier to respond to your post.

[anton478]

Thanks, my program works now. And thank you for letting me know about code tags, I appreciate it.

[Stephanie16]

Thank you as well because I was wondering how to use this code tag. @AbstractionAnon