Hi this is Anil from learning Lad and welcome
to another video tutorial on the C programming language now in the previous videos we have learnt
about the computers and the C programming language and in this video we are going to
see all the steps involved from writing a C program to generating an executable file
from that C program. the first thing is C is a general purpose
programming language and by using the C programming language, we can write the instructions or
the computer programs. Now the instructions written in any programming
language in human readable format is called as the source code and here the instructions
written in the C programming language is called as the C source code now when we write a computer program, we are
going to store that in the Computer memory as the computer file and the file which is
containing this source code is called as the source file and if the file is containing
the source code written in the C programming language then that file is also called as
the C source file. now as I said before we are going to write
the instruction using the C programming language and then we are going to save that in the
Computer memory. so to write the instructions or to write the
code we are going to use the text editors. you can use any text editor available and
you can write the C program and you can save that as a computer file. now while writing in the C programming language
this C programming language it provides a lot of built-in features to implement the
common operations that we have to do in the program. for example in programming, someone has to
frequently perform the input and output operations or programmers have to work on the string
values. so for all this common operations the C programming
language provides the built-in features. so the programmer can just use that built-in
features and then he can write the programs and these features are provided in the form
of C standard library. This C standard library contains all the built-in
features that will perform the common operations that a programmer have to perform in his program.
so while writing the C program you are going to use that built in features and then you
will write the program and we will talk more about this when we write the program and just
now remember that C programming language provides a lot of built-in features that we can use
in our program and we can easily write the programs. And the next thing is as I said before we
are going to write the C program using a text editor and then we are going to save that
in the Computer memory as a computer File. so the next thing is how we can differentiate
a file which is containing the C programming language from any other file. for example if
we have a text file then that text file will have .TXT extension. so by looking at this
.TXT extension we can say that that file is a text file.
similarly for the music files which have the MP3 format will have .MP3 extensions and similarly
the PDF files have .PDF extension. so similar to all these files, the file which
is containing the c source code will be saved with dot C extension.
so here you can give any name to your file while saving it but you have to make sure
that it has the extension dot C. for example if I write a program using C programming
language by using a text editor and then while saving that file I can give any name. for
example I can name it one. but it should have the extension dot C.
so my file has to be saved as one.c This .C will indicate that it is a file containing
the program written in the C programming language. and now the next thing is once we write the C program
using the C language you know we can’t directly execute that code in a computer.
That’s because the computers they can only understand the code which is written in the
binary language or the machine code. and that’s why we need to convert the source code that
we have written in the C language to machine code and we can do that by performing the
compilation process. so we will perform the compilation process
and we will convert this code to the machine code and that machine code generated by this
compilation process is also called as the object code. This compilation process, it will take the
source code written in the C programming language and then it will generate a new file containing
the machine code representation of the source code. and now here the file containing this object
code is also called as the object file and if you are performing this compilation process
in the windows environment then this object file containing the object code will have
.OBJ Extension and if you are performing this in the Linux or Unix environment then this
object file containing the object code will have .O extension. now here during this compilation process several
programs are used. One of the program which is used in the compilation
process is the preprocessor. here before the actual compilation process,
your Source code written in the C programming language will be processed and as the name
indicates this preprocessor is a program, it takes the source code and then it will
perform some operations on it. for example it will remove the new lines and
spaces that you have in the source code and also it will remove the comments and also
it will expand the header files. I know all of you guys can’t understand this
header files and comments. you will I know learn about that later but just remember that
this is preprocessor is a program which is called during the first stage of this compilation
process and it will process this source code and then it will generate an optimised version
of the source code and then that optimised version of the source code produced by this
preprocessor will be given to the compiler. and here since we are talking about the C
programming language it is gonna be a c compiler and this c compiler will generate the machine
code from the source code given to it. so here there are different C compilers are
available and although they perform the same thing, converting the source code written
in C language to the machine code, they work a bit differently some of the compilers they
take the source code and then they generate the Assembly code and then that assembly code
has to be converted to machine code. and some C compilers they directly generate the machine
code from the source code given to them. so here to programs are mainly used and the
first one is the preprocessor. this preprocessor will take the source code
written in the C programming language and then it will produce the optimised form of
the source code and then that optimised source code which is produced by this preprocessor
is given to this c compiler and then this C compiler will generate the machine code
which is also called as the object code. now here what you can do is you can divide
your program in separate files. for example let’s say you are writing a project
using the C programming language and your project contains more than 10000 lines of
C programming language instructions. so at that time if you have that more than
10000 lines of code in just one single file then it will be difficult for you to manage
your project. instead of that if you can do at that project
into several different parts and also into several different files then it will be easy
for you to manage the code. so while writing the programs in the C programming
language you can divide your project into several different files. for example I can
have different files here. for example one.c then two.c and then three.c I can have any number of files which is containing
the C source code. now here if your project contains more than
one file containing your programs then you have to individually compile each of them
and generate the object code. so you have to perform the compilation process
on this one.c and then you have to generate the object code for this one.c and then for
this two.c also you have to do the same thing and for this three.c also you have to do the
same thing. so for each file which you have in your project,
you have to perform the compilation process and you have to generate the object code for
that respected source files. so now here and I’m gonna assume that my
project that I’m building has three files containing the instructions written in the
C programming language. so one.c two.c and three.c
so I have to perform this compilation process on each of them and I have to generate the
object code for each of them. So here after the compilation process I have
the object code of these three files. so let’s say one.OBJ and two.OBJ and three.OBJ All Right.
now this object file is generated after this compilation process.
Now here during this compilation process the compilers may detect some errors in your programs.
so at that time the compilers will generate the errors instead of creating the object
file. so if your program is containing the errors
then the compilers will generate error and you have to go back to your source code and
you have to solve those errors. so if your program contains errors then this
compilation process will detect that then you have to go back to your source code and
you have to correct the error and after correcting the errors you have to again perform this
compilation process and at that time if your program is not containing any error then the
object code will be generated. so once you get your programs error free then
the object Files will be generated. now the next thing is now we have the object
files which is containing the machine code for our project. now that we have to do is we have to link
all these files together and we have to generate an executable.
And for that purpose a program is used and it is called as the linker.
and this linker, it will take the object files, all of them and then it links them together
and then it generates the executable file and in the windows environment this executable
will have the .EXE Extension and similarly for the different platforms they have their
respected the executive extension. And here it takes the object files and also
I have said before while writing the C program you are going to use the features provided
by the C language and that features are provided in the C standard library.
so this linker will link the features that you have used from the C standard library
with your code and then it will produce the executable.
so if your project is containing only one file then it will take that one file and then
if you have used any library functions in your program then it links them together
and produces the executable. And similarly let’s say your project is containing
3 files and then after the compilation process you will get the three object files and this
linker will take that 3 object files and also it links them together and also it links
the standard library functions that you have used and then it produces the executable. now we have this executable file which can
be executed in a computer. now during this linking process also the linker
may find out that your program is containing some errors.
for example let’s say you have made some mistakes while including or while using the features
provided in the standard library. so at that time the linker will generate the
error saying that it can’t link the files. so again you have to go back to your source
code and you have to find the error that you have made in your source code and then you
have to correct that. And after correcting that you have to perform
all the steps again. you have to compile them and then we have to link them.
if there are no errors then the linker will successfully create the executable. now that thing that we have to do once we
get an executable is, we have to execute that program and for that purpose a program is
used and that is called as the loader. this loader will take your executable and
it will load that to the primary memory which is the RAM stand for Random Access Memory
and then the processor will execute it. And here after executing your program, your
program May work or may produce the result successfully or it may not work properly.
for example let’s say you have written a program to calculate the area of a triangle and in
your source code lets say you have done a mistake while writing the formula to calculate
the area of the triangle. so that’s why you will not get any error because
the computer doesn’t know the formula to calculate the area of a triangle.
you have to provide that correctly. but you have done the mistake In that.
that’s why you will get to this execution stage but your program it will not produce
the proper results. it will generate improper results.
and that’s why if your output after executing your program is not proper then also you have
to go back to your source code and you have to correct your program. And then you have to perform all these operations
again, and then you have to execute your program. so this is the steps involved from writing
a C program and then creating an executable and then executing that executables generated.
Now the thing is all these programs which are required to generate the executable from
the C program source file, they come in a bundle. so you have to install a bundle which contains
all these software’s and that bundle is called as the tool set.
so once you install a tool set for the C programming language, you will get all these softwares.
you won’t get the editor you can write it in any text editor but you will get all these
programs for example to perform the compilation process and for this linking purpose and all
those softwares will be available in this tool set. There are many tool sets available for example
we have the GCC tool set and we have Turbo C and also we have the Microsoft specific
visual C++. You know all these tool sets are available
they provide all these programs. so you just need to install the toolset, and
then you will get all these programs then you can build and execute your program. so this is it guys, this is all about the
steps involved from writing a C program to generating an executable from it and then
executing that generated executable file. and if you like this video then give a thumbs
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