A small C library tutorial

This is a small tutorial that introduces how to create a small C library.

Contents

Creating an example C library

This is a small tutorial about how to create a small C library.

First we create the header file "lbi.h": 

void func_a();

float func_b(int, float);

char *func_c(int *, int);

And the implementation "lbi.c": 

#include <stdio.h>
#include "lbi.h"

void func_a()
{
    printf("Hello, func_a\n");
}

float func_b(int a, float b)
{
    return (((float)a) + b);
}

char *func_c(int *ar, int n)
{
    int i;
    char *s = "Hello, func_c";
    for (i = 0; i < n; i++)
    {
        printf("ar[%d]: %d\n", i, ar[i]);
    }
    return s;
}

Using gcc, we can compile this small lib with:

gcc -c lbi.c
gcc -shared -o liblbi.so lbi.o

This produces the small lib liblbi.so that we can link with -llbi.

You can add more functions to it for your experimentations.

Linking

Compile with the parameter -llbi to link with the lib:
liblbi.so. 












Testing the library




  Now that we have liblbi.so we can test with gcc
  in the console.

  We can define LD_LIBRARY_PATH so that our example lib will
  be found correctly:





$ export LD_LIBRARY_PATH=$(pwd)

$ echo $LD_LIBRARY_PATH
/tmp/lib-tut












Arrays




  arrays:

  TODO














Chars




  Arrays of char's:

  TODO











Static Libraries




  Compile with the -static parameter to create a static
  library.






  Static libraries usually have a
  .a file extension.













Difference between Static and Dynamic libraries




  TODO












Conclusion, going further




  TODO












Version of this document




2023-06-29.b











License



© 2019 2021 2022 2023 Florent Monnier




  You can use this document according to the terms of either one of
  these licenses:










  You can reuse the pieces of code according to the terms of either
  one of these licenses:










  
  back