1. What are pointers?
All data of a program are stored in memory.
In memory it is referred with a Unique number called ADDRESS.
Way of accessing that address using variables is called pointers.
Operators used in pointer are
& - address operator.
* - Dereferencing operator,
Example:

int*iptr; is an integer pointer.

2. What do you mean by Type Casting?
Converting data of one data type into data of another data type is called as type casting.
Type casting can be done only between compatible data types.
While converting if the assigned data is longer it will be truncated.
Example:-

int a;

float f=10.33

a=(int)f; - 10 will be stored in a and .33 will be truncated.

3. Define Character Constant.
A constant that contains a single character.
A character constant can be an, alphabet, numeral, symbol or non-graphic character.
Any character which forms part of ASCII character SET.
A Character constant is enclosed within Single Quotes(` `)
Example:-

‘a’,’+’,’3’,’\n’

4. Define Integer Constant.
A constant that contains a whole numbers.
Must have at least one digit.
Cannot have fractional or exponential part.
Can be signed or unsigned.
Example:-
10,20,1,3000,32767.