Simple C++ Error: “… undeclared (first use this function)”

Question

I am working on my first C++ program for school. For some reason I am getting the following error when I try to compile it:

`truncate\' undeclared (first use          


        

Answer 1

You need forward declaration before your main:

double truncate(double d);
double round(double d);

You could just define your functions before main, that will solve the problem too:

#include 
#include 

using namespace std;

#define CENTIMETERS_IN_INCH 2.54
#define POUNDS_IN_KILOGRAM 2.2

// round result
double round(double d) {
   return floor(d + 0.5);
}

// round and truncate to 1 decimal place
double truncate(double d) {
   return round(double * 10) / 10;
}

int main() {
...
}