shared memory in C

A shared memory is nothing but a piece of memory shared across multiple process.

vim editor commands

Copy paste text between different files

git tutorial. Use git locally or with Dropbox

I have been working on a project for which I need to restore to different state of the project. I searched and I got an elegant solution.

A problem; what is the difference between signed and unsigned ?

I was looking at the disassembled code of 2 programs compiled with gcc. In one program I initialised an unsigned variable and in the next program I initialised the same variable as signed.

Static and Shared libraries with C

This post explains how to use static and shared libraries with C. My platform is gcc version 4.4.3 (Ubuntu 4.4.3-4ubuntu5).

Install basic required applications in Ubuntu 10.04 LTS - Lucid Lynx

LTS means long term support. So this version of Ubuntu is  a nice flavor. But the main problem with open source OS is it will be just an OS without the some good applications.

C programs and Makefile, sources, objects, libraries!!?

If we have a number of C sources and header files then how to create an executable from all these. This post is a template for that concept. This post contains a Makefile which is a simple but standard makefile which can be used as a template. I thought of writting this when I started working on embedded programs with C.This post not explains shared library concept.


Take the simplest case, a single main.c file.


#include <stdio.h>


int main ( void )
{
   printf("This is a test\n");
   return 0;
}
compile it: $gcc -o main main.c
$./main will print the result.

Consider another situation where we have functions defined in different files/directories. Then how to compile to create an executable. Here comes -c, -o options and object file concepts.

I am not writting any explenation for this. Create the following files in a directory and experiment.
Consider we have three functions and a header file another.c  define.h  functions.c  main.c

main.c

--------

#include <stdio.h>

int main ( void )

{

printf ( "%s\n", "This is a printf from main function" );

function_one();

return 0;

}

functions.c

--------------

#include <stdio.h>

#include <define.h>

void function_one ( void )

{

printf("function_one has been executed. The defnition is: %d\n", NUMBER );

another_fun();

}

void function_two ( void )

{

printf("function_two has been executed.\n");

}

another.c

-----------

#include <stdio.h>

void another_fun ( void )

{

printf ( "Another function\n" );

}

define.h

-----------

#define NUMBER 142

Makefile

-----------

CC := gcc 

OBJECTS := functions.o main.o another.o

INC1 := ./

INCLUDES := -I$(INC1)

bin: $(OBJECTS)

$(CC) $(OBJECTS) -o bin 

functions.o: functions.c

$(CC) $(INCLUDES) -c functions.c -o functions.o

main.o: main.c

$(CC) -c main.c -o main.o

another.o: another.c

$(CC) -c another.c -o another.o

clean:

rm -rf bin *.o