GCC Compile Error

I wrote the following program in Visual Studio 2010 Express and its execution resulted in no errors or warnings.

I am now receiving the following GCC compile error after attempting to compile it in a command-line linux environment:

gcc -o mpg.o -c mpg.c

"error: expected â;â, â,â or â)â before â&â token"

The above error is being generated by lines 43 and 56 of my code (mileage_calculator and gas_calculator function definitions).

This seems more like a compiler specific issue to me. Would I be able to use some differenct operators to get this to compile? If the issue is not compiler specific and I've written bad code, I would rather struggle and figure it out on my own. I hope this makes sense.

Code:

---

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

double l_mpg = 0;
double u_mpg = 0;
double d_mpg =0;
double i_gph = 0;

double distance = 0;
double min = 0;
double miles = 0;
double gas = 0;
char terrain = ' ';

char get_terrain()
{
    scanf(" %c", &terrain);
    terrain = toupper(terrain);

    if(terrain != 'L' && terrain != 'U' && terrain != 'D' && terrain != 'I' && terrain != 'E')
    {
        printf("Bad Input.\n");
        exit(0);
    }
    else
        return terrain;
}

double get_distance()
{
    scanf(" %lf", &distance);

    if(terrain == 'I')
    {
        min = distance;
        distance = 0;
    }

    return distance;
}

double mileage_calculator(double &d)
{
    miles = miles + d;

    if(miles <= 0)
    {
        printf("Bad Input.\n");
        exit(0);
    }
    else
        return miles;
}

double gas_calculator(char &t, double &d)
{
    switch(t)
    {
        case 'L':
            gas = gas + (d / l_mpg);
            break;
        case 'U':
            gas = gas + (d / u_mpg);
            break;
        case 'D':
            gas = gas + (d / d_mpg);
        case 'I':
            gas = gas + (min / 60) * i_gph;
            break;
        default:
            break;
    }

    return gas;
}

int main()
{
    printf("Enter Fuel Economy: ");

    scanf(" %lf %lf %lf %lf", &l_mpg, &u_mpg, &d_mpg, &i_gph);
   
    if(l_mpg < 0 || u_mpg < 0 || d_mpg < 0 || i_gph < 0)
    {
        printf("Bad Input.\n");
        exit(0);
    }

    printf("Enter Terrain & Distance: ");

    get_terrain();

    while(terrain != 'E')
    {
        get_distance();
       
        mileage_calculator(distance);

        gas_calculator(terrain, distance);

        get_terrain();
    }

    printf("Miles=%8.2lf\tGallons=%8.2lf\tMPG=%8.2lf\n", miles, gas, miles/gas);

    return 0;
}

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I am an inexperienced programmer in the learning stages. I am stuck after attempting to research a solution. Your assistance is greatly appreciated.

This program is C++, not C. You can tell based on the line

Code:

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double mileage_calculator(double &d)

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To compile the program with GCC, use the command g++ instead of gcc.
Or even better, rewrite the program as valid C (assuming you're trying to learn C). In C, pointers are used rather than reference variables.

If not doing C++;just change this

Code:

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double mileage_calculator(double &d)

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to this

Code:

---

double mileage_calculator(double d)

---