Creating Header Lib

Introduction

You will learn how to create and maintain my own library/header file

For this tutorial, we will create ;

• Declare all your functions in myNM_tutorial.h

• Define all your functions in myNM_tutorial.c

• Include your library in main sourceC_createHeader_example.cpp

  Don't worry about the file extension of *.cpp or *.c

  You can use either extension with Visual Studio for Numerical Programming course

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Step 1. Workspace Folder

Create local directory for programming

We will create the main directory under

C:\Users\yourID\source\repos

e.g. C:\Users\ykkim\source\repos

You can search for 'repos' in window menu

image

This is where your assignment projects should be located.

For this tutorial, let us create the new workspace directory as

• Name the directory as "NP"

  A name that clearly shows the course name

Create more necessary sub directories

Example:

• C:\Users\yourID\source\repos\NP

• C:\Users\yourID\source\repos\NP\tutorial

• C:\Users\yourID\source\repos\NP\include

Step 2. Create a tutorial C Project

Under \tutorial Directory, create a new folder named as TU_createheader

• C:\Users\yourID\source\repos\NP\tutorial\TU_createheader

Create a new empty project in Visual Studio Community. Name the project as TU_createheader

Create a new C/C++ source file for main()

• Name the source file as C_createHeader_example.cpp

Paste the following code or download src file from here

#include "stdio.h"
#include "stdlib.h"

// Include path will be included at the end of tutorial
// #include "myNP_tutorial.h"


void printVec(double* vec, int row);

int main(int argc, char* argv[])
{

	double x[3] = { 1, 2, 3 };
	int x_size = sizeof(x)/sizeof(double);

	printVec(x, x_size);

}


void printVec(double* vec, int size)
{
	for (int i = 0; i < size; i++)
		printf("Vector[%d] = %.1f \n", i, vec[i]);
	printf("\n");
}

Part 2. Create your Header files

Under the directory of \include, create 'myNP_tutorial.cpp' and 'myNP_tutorial.h'.

• C:\Users\yourID\source\repos\NP\include

• You can download source files here

Do not make duplicate copies of these files in your local drive. Update these files as you do assignments.

myNP_tutorial.h

#ifndef		_MY_NP_H		// use either (#pragma once) or  (#ifndef ...#endif)
#define		_MY_NP_H

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

extern void printVec(double* vec, int row);

#endif

myNP_tutorial.cpp

// Change the directory path
#include "../include/myNP_tutorial.h"

void printVec(double* vec, int size)
{
	for (int i = 0; i < size; i++)
		printf("Vector[%d] = %.1f \n", i, vec[i]);
	printf("\n");
}

Part 3. Include your Header files

In the above main() program, include your header library by finding the path.

Now, you need to delete the function definition of printVec() in main(), for we have included the function from the header library file.

The main source file should be modified as

#include "stdio.h"
#include "stdlib.h"

// Change the Include path 
#include "../../../include/myNP_tutorial.h"   // Find the location of header files


// #include "myNP_tutorial.h"   // if the PATH is already Included in Project

#include "stdio.h"
#include "stdlib.h"

// Include path will be included at the end of tutorial
// #include "myNP_tutorial.h"


void printVec(double* vec, int row);

int main(int argc, char* argv[])
{

	double x[3] = { 1, 2, 3 };
	int x_size = sizeof(x)/sizeof(double);

	printVec(x, x_size);

}

// void printVec() definition is deleted in main source

Compile and run the program.