Using static libraries

[steve1_rm]

Hello,

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

//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:

//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:

#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

[brewbuck]

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?

[prog-bman]

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.

[anon]

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

[prog-bman]

Not to my knowledge.

[steve1_rm]

Hello,

Thanks it worked.

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