Using static libraries

Hello,

I have developed a static library. The header for this static library is below:

Code:

//MathFunctionsLib.hpp

namespace MathFunctions
{
	class MyMathFunctions
	{
	public:
		//Return a + b
		static double Add(double a, double b);

		//Return a - b
		static double Subtract(double a, double b);

		//Return a * b
		static double Multiply(double a, double b);

		//Return a / b
		//Throws DivideByZeroException if b is 0
		static double Divide(double a, double b);
	};
}

Source file below for that uses this header file:

Code:

//MathFunctionsLib.cpp

#include "MathFunctionsLib.hpp"
#include <stdexcept>

using namespace std;

namespace MathFunctions
{
	double MyMathFunctions::Add(double a, double b)
	{
		return a + b;
	}

	double MyMathFunctions::Subtract(double a, double b)
	{
		return a - b;
	}

	double MyMathFunctions::Multiply(double a, double b)
	{
		return a * b;
	}

	double MyMathFunctions::Divide(double a, double b)
	{
		if(b == 0)
		{
			throw new invalid_argument("b cannot be zero");
		}

		return a / b;
	}
}

I compiled this library into a object file using the following which worked ok.
g++ -I MathFunctionsLib.cpp -o MathFunctionsLib.o

Then creating the archive
ar rcs libMathFunctions.a MathFunctions.o

The directory structure I have for linking this library into an existing project.
src/calculator.cpp
include/MathFunctionsLib.hpp
lib/libMathFunctions
bin

The calculator program that will use the library is this:

Code:

#include <iostream>
#include "MathFunctionsLib.hpp"

using namespace MathFunctions;

int _main(int argc, char** argv)
{
	double a, b, answer;

	answer = MyMathFunctions::Add(10, 10);
	std::cout << "The answer is: " << answer;
	
	getchar();

	return 0;
}

I am using kate as I am using Kubuntu to compile my programs
Projects/Calculator/src$ g++ -o ../bin/Calculator MyCalculator.cpp -I ../include -L ../lib -llibMathFunctions

However, when I try and compile the program and link with the library I get the following error message:
/usr/bin/ld: cannot find -llibMathFunctions
collect2: ld returned 1 exit status

Can anyone tell me where I am going wrong with this.

Many thanks for your time,

Steve

Use -lMathFunctions, not -llibMathFunctions. The lib part is always implicit.

Also, why does your test program have "using namespace MathFunctions" when you then go and fully qualify the names anyway?

They are in the namespace MathFunctions, but his class name is MyMathFunctions. So he is calling the static member of the class in that instance.

Is a class that contains nothing but static functions really any better than a bunch of free functions (possibly in a namespace)?

Not to my knowledge.

Hello,

Thanks it worked.

steve@steve01:~/Projects/Calculator/src$ g++ -o ../bin/Calculator MyCalculator.cpp -I ../include -L ../lib -lMathFunctions