variable initialisation in c programming!

 what happens exactly if one typed as code below?

main()
{
  int a=10;
}

Here the compiler starts begins compiling from main() function.(Every C program begins with main() function )
when a compiler reached third step i.e., int a=10; it allocates 2 bytes of memory in main memory whose name is a and a contains the values 10. What exactly it doing is we can compare it like this-

   suppose a person needs a house.So he needs a space(here 2 bytes) and he needs a name of house(here a) and he stays in house(here 10).

what happens if one typed code as given below?

main()
{
  int a,b=5;
  float c=10.5;
 }

Here the compiler starts begins compiling from main() function and allocates two bytes of memory for a whose value is 10. It allocates four bytes of memory for  c.
But for b it allocates two bytes of memory and we have not given any value to c.
(NOTE: c contains garbage value we discuss later in storage classes about garbage value)




important points to remember:

                                    numbers are divided into two types in c 
                                     integer numbers and fraction numbers. 

           integer numbers are stored in memory using int datatype and c compiler  allocates two bytes of memory.
           fraction numbers are stored in memory as float data type and c compiler allocates four bytes of memory.

  Data types and memory sizes in C.

    datatype name                              size                                    example
     int                                                2bytes                                -123,   0,  345,
    float                                              4 bytes                               -4.5 , 0 , 3.76
   char                                                1 byte                                a, b, c        

int a=10;   /* here a is integer variable whose value is 10*/
float b=4.5;  /* here b is a float variable whose value is 45*/
 char c='a';   /* here c is character variable whose values is a*/
        (note: character variable must be enclosed in single quotes)

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