trouble with error code

/* This program */

using namespace std;

#include <iostream>
#include <cmath>
#include <iomanip>
#include <fstream>

void readit();
void calcit(int, int);
void writeit(float, float, float);
int distvels[4] = {15, 25, 35, 45};

int main()
{
    readit();
    system("pause");
    return 0;
}

void readit()
{
     int targetdist, angl;

     cout << "Enter the distance (meters) to the target:" << endl;
     cin >> targetdist;
     cout << "Enter the angle to fire the cannon:" << endl;
     cin >> angl;
     cout << "\n---------------\n\n";
     calcit (targetdist, angl);
}

void calcit(int targetdist, int angl)
{
     double distvals[4];
     double tyme[4];
     double maxhite[4];

     for (int i=0; i<4; i++) {
         distvals[i] = (2 * sin(angl) * cos(angl) * (distvels[i] * distvels[i]))/9.8;
         tyme[i] = (2 * cos(angl) * distvels[i])/9.8;
         maxhite[i] = ((cos(angl) * cos(angl)) * (distvels[i] * distvels[i]))/9.8;
     }

     writeit(distvals, tyme, maxhite);     
}

void writeit(float distvals[4], float tyme[4], float maxhite[4])
{
     cout << "Velocity       " << "time      " << "height     " << "distance    " <<endl;
     for (int i=0; i<4; i++) {
         cout &l开发者_Python百科t;< distvals[i] << " " << tyme[i] << " " << maxhite[i] << " " << endl;
}

whenever I run the program I keep getting this error code cannot convert double* to float for argument 1 to void writeit(float, float, float). I've tried everything I can think of to get rid of it with no luck. Can anyone help?

---

You declared the function as:

void writeit(float, float, float);

but the definition has it as:

void writeit(float distvals[4], float tyme[4], float maxhite[4])
{
    // ...
}

Fix the declaration to match:

void writeit(float[4], float[4], float[4]);

---

It's also worth pointing out at this juncture that this doesn't do what you think it does. In fact, it's the same as this:

void writeit(float[], float[], float[]);

which is the same as this:

void writeit(float*, float*, float*);

That's because you can't pass an array by value, so it degrades into a pointer-to-the-start-of-the-array instead.

However, you can pass it by reference and keep the dimensions:

void writeit(float (&)[4], float (&)[4], float (&)[4]); // declaration
void writeit(float (&distvals)[4], float (&tyme)[4], float (&maxhite)[4]) // definition
{
    // ...
}

I'd even recommend passing it as reference-to-const, as you won't be changing it:

void writeit(float (&)[4], float (&)[4], float (&)[4]);
void writeit(const float (&distvals)[4], const float (&tyme)[4], const float (&maxhite)[4])
{
    // ...
}

It would also be easier if you used a std::vector<float>, but that's another discussion.

Plenty to think about there; hope it helps.

---

Edit Just noticed another problem, in that you're trying to pass an array of double to a function that will be expecting an array of float! Pick one and stick with it.

---

The error is exactly as you note -- writeit is expecting a pointer to an array of floats and you're trying to pass it an array of doubles, which are a different size. The easiest fix would be to declare the args of writeit to be arrays of doubles, so they match. Barring that, you need to copy to arrays of floats before passing (converting each element as you copy)

---

The function prototype is different from the function definition. So, change it to -

 void writeit(double*, double*, double*);

And the function definition to -

void writeit(double distvals[], double tyme[], double maxhite[])
{
     // ......
}

Notice that the array size (i.e., optional, in fact compiler won't consider it) because array decays to a pointer. It is the reason why usually array size is also sent as an argument to the functions and is a good practice.