BCA 2nd Sem Notes- Masks

• UNIT-I (Array)

Definition

Declaration & initialization of 1D 

Accessing array elements

Displaying array elements

Sorting arrays

Arrays and function

Declaration & initialization of 1D

Accessing and Displaying

Memory representation of array [Row Major, Column Major]

Multidimensional array

UNIT-II (Pointers)

Definition

Declaration & initialization

Indirection operator

address of operator

pointer arithmetic

dynamic memory allocation

arrays and pointers

function and pointers

UNIT-III (Strings)

Definition

Declaration & initialization

standard libraryfunction strlen()

strlen(),strcpy(),strcat() ,strcmp()

Implementation without using standard library functions

UNIT-IV (Structures)

Definition

Declaration & initialization

Accessing fields

structure operations

Nested structures

Union: Definition  declaration

Differentiate between Union and structure

UNIT-V                                  (C Preprocessor)

Definition
Macro substitution directives
File inclusion directives
Conditional compilation
Bitwise Operators
Shift operators
Masks
Bitfield

UNIT-VI                                (File Handling)

Definition of Files,
Opening modes of files
Standard function
fopen(), fclose(),               feof() fseek(),                     fewind()
Using text files
fgetc(), fputc(),               fscanf()

Program's in C

Masks

Masking is the process or operation to set the bit on to off or off to on in a byte, nibble or word.

1. Mask means to block.
2. Masking is the process by which, only required data is retained and the rest is masked (blocked)
3. Masking can be done using Bitwise Operators
4. Most Commonly Used Bitwise Operator is AND(&)

A mask defines which bits you want to keep, and which bits you want to clear.

Masking is the act of applying a mask to a value. This is accomplished by doing:

• Bitwise ANDing in order to extract a subset of the bits in the value
• Bitwise ORing in order to set a subset of the bits in the value
• Bitwise XORing in order to toggle a subset of the bits in the value

Below is an example of extracting a subset of the bits in the value:

Mask:   00001111b
Value:  01010101b

Applying the mask to the value means that we want to clear the first (higher) 4 bits, and keep the last (lower) 4 bits. Thus we have extracted the lower 4 bits. The result is:

Mask:   00001111b
Value:  01010101b
Result: 00000101b

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