Interview Questions

                                                       

1.    What are different types of storage classes in c?
A.    There are 4 storage classes in c ie
                 i)Automatic
                 ii)Register
                 iii)Static &
                 iv)External

         i) Automatic(Auto):
                        Storage: Memory
                         Default Initial Value: Garbage Value
                         Scope: Local to block in which variable is declared.
                         Life: Till the control remain with in block in which variable is declared

         ii) Register:
                        Storage: CPU Registers
                         Default Initial Value: Garbage Value
                         Scope: Local to block in which variable is defined.
                         Life: Till the control remain with in block in which variable is defined.

         iii) Static:
                       Storage: Memory
                        Default Initial Value: Zero
                        Scope: Local to block in which variable is defined.
                        Life: Till value of the variable persists between different function call

         iv) External:
                        Storage: Memory
                         Default Initial Value: Zero
                         Scope: Global
                         Life: As long as program's execution doesn't come to an end.
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2.   What is meant by pointer?
A.   It is an Operator(*). It is called Value at address.

• Can be applied to any data type
• Declaration 

                             int *j;

                             int i=10;  

                             j=&i;

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3. What is meant by "float *s"?

A. It stores the address of floating point variable but not the floating point value.

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4. How to declare 'pointer to array'?

A.  Int (*p)[2]

             

                      Brackets to p are necessary

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5. How to declare 'array to pointer'?

A. Int *s[4]

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6. How to declare 'pointer to function'?

A. Every function in C is associated with some address

      Declaration:       int display();

                                    int (*fun-ptr)();     (parenthesis are necessary)

                                    display=fun-ptr;  (address assignment)

                                    (*fun-ptr)();          (invokes the function display)

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7. What is meant by Structure and how to declare it?

A. It is defined as that the data type in which it stores Dissimilar datatypes.

                 Declaration:  

                                            struct  book                      (new data type)

                                             {

                                                 char name;

                                                  float price;

                                                  int pages;

                                             };

   

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8. Is it possible to declare any number of variables in structure?

A. Yes, it is possible to declare any number of variables 

                eg: struct book b1,b2,b3

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9. What are features of Structure?
A. * The value of structure variable can be assigned to another structure of same type using              assignment operator
    * One structure can be nested with in another structure.
    * A structure variable can also be passed as an argument to function.
    * Pointer to applicable to structure
    * Main use of structure is database management.
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10.What are the uses of structure?

A.  * Changing the size of cursor

      * Clearing the content of screen

      * Placing the cursor to an appropriate position on screen

       * Drawing any graphics shape on the screen

        * Receiving a key from keyboard

        * Checking the memory size of this computer

        * Finding out the list of equipment attached to the computer

        * Formatting a floppy

        * Hiding a file from directory

        * Displaying directory of disk

        * sending the output to printer

       * Interacting with the mouse.

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11.What is difference between structures and array?

A *Array is collection of similar elements

    *Structure is a data type which stores dissimilar data types.

    * Array is a derived data type

    * Structure is user defined data type.

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12.What is meant by Malloc() ?

A * It is standard library function

*It is used to allocate memory dynamically during the time of execution.

* By using array we get fixed with some size but using malloc() we can create our own required size by passing number of bytes

* Malloc takes single argument

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13.What is Macros?

A Macros are defined labels which can be replaced at any time by the user.

Ex. #define MAX 35

      #define Z Printf (Z is used in place of printf)

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14.What is meant by call by value?

A Call by value is defined as “sending the values of the variable as argument”.

Ex. Swap(x,y);            ………….> Function calling

  Swap(int a,int b)    ……………> Function definition

{ …………………}

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15.What is meant by call by Reference?

A Call by Reference is defined as “Passing the address of the variable as argument”.

 Ex. Swap(&a,&b);      ………….> Function calling

 Swap(int *x,int *y)    ……………> Function definition

{……………}

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