Compilation Process in C

Compilation

The conversion of source code into object code is known as compilation.This process is done with the help of compiler.

below is a full diagram of showing how source code convert into software(i.e software development in c)

Explanation:-

Source code :- the c programming coding is known as source code. save your programe with .c extension then your file become source file for example in fig: sum.c is a source file in which source code is written to print a hello.

Prerocessor :- first we need a preprocessor software to convert source file (i.e .c file).Preprocessor handle all those statement which is starting from # symbol.

Header file :- In our programe as seen clearly in sum.c we did not create any header file (i.e which start from # symbol) we just use it.Preprocessor add the content of header file in our source file and creates a new file this file same as our source file but only difference is that the header file removed from the new file which is in .i extension as above sum.i

Compiler :- the new file (i.e .i extension file) is made by preprocessor. now this file is compiled by compiler.Compiler also creates a new file i.e object file means in .obj file. compiler are of different -2 types for every platform.

Library files :- now we need a library files because in object file there are many code written which cannot understand by operating system but the meaning of those codes are present in library files.

Linker :- now we need a linker. Linker link the library file into object file and creates a new file which is .exe file(i.e software).

Comments

Type casting

type casting or type conversion allows us to convert one data types into another.for type casting cast operator is required. Syntax:-- (type)expression or value; Example: int f =9/4; //without type casting o/p=2 float f=(float)9/4; //with type casting o/p=2.3 Type conversion are of two types: 1)Implicit Type Conversion:- it is also known as automatic type conversion.When the type conversion is performed automatically by the compiler,such type of conversion is known as implicit type conversion. 2)Explicit Type Conversion:- the type conversion performed by the programmer is known as explicit type conversion.which is done by cast operator as above mentioned.

CALL BY VALUE AND REFERENCE--

A function can be called by two types 1) Call By Value:- when an original value is not modified , is known as call by value. In call by value the actual parameter(the parameter passed to function) is copied into the formal parameter(parameter receive by function). in this the value of each variable in calling function is copied into the corresponding dummy variable of the called function. the changes made to the dummy variable have no effect on the actual variable. Example:- 2)Call By Reference:- when an original value is modified, is known as call by reference.in this a reference is used , denoted by &(symbol). we can use either pointer or reference for call by reference in this the address of the variable is passed into the function called by actual parameter. in this the memory allocation is same for both actual and formal arguments. Example:-

UNION

Definition:- Union is similar to structure, except it allows you to define the variable that share storage spaces.Defining a means creating a new data types. How use union:- when we create a structure by using struct keyword, now making a union we just replace the keyword struct with the keyword union , other syntax will be same. Difference between Structure and Union:- the only difference between them is in memory. NOTE:- union is used for low level programming but structure mostly used for high level programming. Program to access union:- """SHARE IT WITH YOUR FRIENDS IF HE DID NOT KNOW""""

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