noob error returning a function evaluation

I can't seem to figure out why this isn't returning the quotient of inches*2.54, even though I think to convert from inches to centimeters it should be inches/2.54. Anyways I can't get that value, I either get a warning saying "the address of 'float inches_to_centimeters(float)', will always be 'true' " or else I get an error saying something about the stuff under the { after if. I only get the error when I change the return in the function to "return (inches*2.54);
Here's the code, if anyone can help...

Code:

/*
 * Name : xxxxxx xxxxxxx
 * Course : cps
 * Assignment : Homework03
 * Description : Convert from english units to metric and vice versa. 
 */

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

float inches_to_centimeters(float inches);
int main()
{
  string conversion;
    cout << "Please enter the name of the units you would like to convert to" << endl;
    cout << "   -Ex. to convert from inches to centimeters, enter \"inches\"" << endl;
    cout << "The following are the available conversions: " << endl;
    cout << "    inches, centimeters, feet, meters, miles, kilometers" << endl;
    cin >> conversion;
    if (conversion == "inches")
      {
    float inches_to_centimeters(float inches);
       cout << inches_to_centimeters << endl;
      }
    else
      {
    cout << "no" << endl;
      }
}
/*
 * Name: inches_to_centimeters
 * Purpose: Convert inches to centimeters
 * Receive: A number in inches
 * Return: Equivalent number in centimeters
 */

    float inches_to_centimeters(float inches)
      {
    cout << "The number of inches is: ";
    cin >> inches;
    (inches*2.54);
    return 0;
      }

Code:

    if (conversion == "inches")
      {
    float inches_to_centimeters(float inches);
       cout << inches_to_centimeters << endl;
      }

When you make a call to a function you do not specify the return type or the type of the parameter.

You need to review how to call functions, how to get a return value, and how to pass parameter.

(inches*2.54);

This has has no affect as the result is not stored.

I originally had it as this

return (inches*2.54);

instead of:

(inches*2.54);
return 0;

Wow, this just makes my head hurt:

Code:

if (conversion == "inches")
      {
    float inches_to_centimeters(float inches);
       cout << inches_to_centimeters << endl;
      }

Seriously, you need to review functions in general. If you have specific questions post them.

Yea, well I figured out that for this program I only needed to make it a test driver, so I didn't need the if statement or anything. I'm just beginning to learn C++ that's why i'm so bad at it. I thank you for your input though.

Here is how a simple function works:

Code:

#include<iostream>
using namespace std;

double simple(int a)
{
    double temp = a * 1.5;
    return temp;
}

int main()
{
    int some_int = 9;
    double result = simple(some_int);
    cout<<result<<endl;

    return 0;
}