datatype

let us understand datatype declaration statement:-

int a,b =5;

After seen this type of line compiler understand that it is a data type declaration instruction(statement).

The first word of that instruction is obviously data types. for ex- here it is int.

We cannot use more than one data types in one line.

Compiler understand that after data type creating a variable, so a and b are the variable or we say the name of memory location.

No. of variable can be created in one line.

In our statement variable a hold the value 5 but not in b.

b variable also hold a value which is unpredictable known as garbage value

so every variable in which value is not assigned hold a garbage value

It is not necessary to initialize a value when variable is declared.int a,b; is a declaration statement other statement except declaration are known as action statement. they come after the declaration not before it is a rule of C.

int a,b; a=5,b=10; initialize after declaration

Comments

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:-

Static Memory Allocation

Statement are of two types:- Declaration:- in which we declare the variable Action:- in which for,if-else,getch,printf,scanf etc are used. SMA(STATIC MEMORY ALLOCATION):- whenever we create a program,there is a line of declaration statement(or data type declarartion statement) such as int a;char b;etc. Due to this statement we create a variable a,now this variable is the example of SMA.SMA means how much memory is consumed by variable at the time of compiler,this decision is taken before the compilation. At the compile time these variable such as a and b does not having a memory.Memory is given when program is run i.e when object file convert into .exe file.But when program is run how much memory is taken by the variable is decided at the compilation time.This is known as SMA(Static Memory Allocation).

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 ...

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