Chapter 18 – Miscellaneous Topics. Multiple File Programs u Makes possible to accommodate many programmers working on same project u More efficient to.

Chapter 18 – Miscellaneous Topics

Multiple File Programs

Makes possible to accommodate many programmers working on same project

More efficient to manage large amount of source code

Can incorporate class libraries in separate files from independent vendors

Lesson 18.1

Using Header Files

Header file is source code file Inserted into program source code before

program compiled Can create own header files Option of having separate files for class

definitions, implementations, and main– Placed in different header files and use #include

Lesson 18.1

Working With Header Files

Creating header file– Source code file with extension .h

Including header files– #include “name.h”

Header file contents– Put each class definition and each class

implementation in separate files

Lesson 18.1

Header File Contents

Three lines needed– Two at top and one at bottom– Messages to preprocessor and not compiled

#ifndef name_h#define name_h…source code…#endif

Lesson 18.1

Preprocessor Directives

#ifdef True if identifier defined in previous preprocessor

#if True block executed if constant expression following is true

#else Forms false block for #if

#endif Marks end of conditional inclusion

#ifndef True if identifier NOT defined previously

#elif Works similar to “else if”

#undef Undefines previously defined identifier

Lesson 18.1

Another Method

More efficient connecting files with IDE– Integrated Development Environment

Save correctly working files as object code Link after all changes have been recompiled

Lesson 18.1

Bitwise Manipulations

Very low-level operations Manipulate individual bits (1s and 0s) C++ provides bitwise operators

– Six operators Bit values

– set if value is 1– clear if value is 0

Lesson 18.2

Why Use Bitwise Operators

To control peripherals To use as flags

– Use individual bits instead of integers File encryption Array handling for any array that has

members with only two possible states

Lesson 18.2

Bitwise Operators

AND & Inclusive OR | Exclusive OR ^

– Also called XOR Complement ~ (unary operator) Right shift >> Left shift <<

Lesson 18.2

Hexadecimal Notation

Lesson 18.2

Hexadecimal Binary Bit Pattern0 00001 00012 00103 00114 01005 01016 01107 01118 1000

bitwise And / inclusive OR

Work similar to counterparts && and ||

1 & 1 = 1, all others evaluate to 01 & 0 = 0, 0 & 1 = 0, 0 & 0 = 0

0 | 0 = 0, all others evaluate to 10 | 1 = 1, 1 | 0 = 1, 1 | 1 = 1

Lesson 18.2

Example (Hex 3 with Hex 6)

Lesson 18.2

Bitwise AND Bitwise ORhex 3 0 0 1 1 hex 3 0 0 1 1 & |hex 6 0 1 1 0 hex 6 0 1 1 0 = =

&&&& | | | |

0 0 1 0 0 1 1 1hex 2 hex 7

Complement Operator ~

Reverses all bits of operand

~(1010) = 0101

Lesson 18.2

Bitwise Exclusive OR ^

Evaluate to 0 if both operands the same

0 ^ 0 = 0 1 ^ 1 = 0

0 ^ 1 = 1 1 ^ 0 = 1

Lesson 18.2

Bitwise Shift Operators

Move all bits in cell either right or left directions

Add clear bits in shift

1 0 1 1 0

0

>>

1

<<

1 0 1 1 0

0 1

Lesson 18.2

Comments

Can shift more than one bit Bitwise operators can only be used on

integer data types All systems do NOT use same bitwise

representations– May get different results

Lesson 18.2

Binary Files

Efficient since do not have to convert from ASCII

Saves execution time Not “human friendly”, text files better Cannot be used with editing software Cannot be printed

Lesson 18.3

Opening Output File for Binary

ofstream out_ob (“name”, ios :: out | ios :: binary);

Lesson 18.3

programmer-chosen output file object namefilename

Opening Input File for Reading in Binary

ifstream in_ob (“name”, ios :: in | ios :: binary);

programmer-chosen input file object namefilename

Lesson 18.3

Writing to File in Binary

out_ob.write (reinterpret_cast<char*> (address), num_bytes);

Lesson 18.3

Programmer-chosen output file object nameAddress of beginning of memory cells being written to file

Number of bytes to be copied from memory to file

Reading From a Binary File

in.ob.read (reinterpret_cast<char*> (address), num_bytes);

Lesson 18.3

Programmer-chosen input file object nameAddress of beginning of memory cells to which bytes are copied

Number of bytes to be copied from file to memoryOperator that makes C++ interpret address to represent beginning of an array of characters

Closing the File

Close file after writing Can open later for reading again

Lesson 18.3

outfile.close ( )

Summary

Benefits of multiple file organization How to use header files How to use bitwise operators How to work with binary files