Analisis Top Down input Output Runtunan · PDF fileAnalisis Top Down input & Output Runtunan...

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Analisis Top Downinput & Output

Runtunan

Pertemuan 3

IF-UTAMA Ver/Rev : 1/0 III - 2

Overview

o Deskripsi

o Tujuan Instruksional

o Referensi

o Overview Library Header

o Analisa Top Down

o Input & Output

o Runtunan


Deskripsi

Pada pertemuan ini akan dipelajari mengenaiAnalisa Top Down, input & Output dalam Bahasa

C/C++, serta runtunan

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Tujuan Instruksional

Mahasiswa diharapkan dapat :

o Menjelaskan analisis Top-Down

o Menjelaskan proses input dan output, serta cara

penulisannya dalam program

o Membedakan proses input dan output

o Menjelaskan proses runtunan/sequence

o Menggunakan analisis Top-Down

o Menggunakan proses input dan output

o Menggunakan proses runtunan/sequence


Referensi

1. Deitel, H.M. and Deitel, P.J., “C++ How to Program, 2nd Edition”, Prentice Hall, 1994 (Bab 3

dan 12)

2. Deitel, H.M. and Deitel, P.J., “C How to Program,

4nd Edition”, Prentice Hall, 2004 (bab 5,8,9 dan21)

3. Herianto,“Presentasi Pemrograman

Terstruktur.ppt”,2004

Header File

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Header Files

Common Usages:

o Creates an informal module interface (No relation to Java interfaces)

o Provides documentation

o Each module usually has a header file

o Often include the following:� function prototypes� struct and class declarations� typedefs� global variable declarations� Lots of (high-level) comments

o Abstracts code for optimization (less common)


Preprocessor Overview

The preprocessor is a lexical macro engine

run before the compiler sees the code

o Performs lexical transforms of text

� It does not understand C/C++� There is no concept of types

o Transforms are based on lexical substitution

� Think Search and Replace

o Preprocess directives (commands) start with ‘#’

� Each directive goes on its own line

� The # must be the first character on a line.

o No semicolons!!!!!!!!!!!!

� Newlines end a preprocessor directive, no a ‘;’.


#define

o #define Tag Substitution

� Replaces all following occurrences of Tag with Substitution

� The Substitution may be the empty string� Does not replace Tag if it is inside quotation marks

o #define Tag(x,y,z) Substitution

� Creates a Function-like macro Tag

� The Substitution may refer to the parameters x, y, or z

� Only items of the form Tag(x,y,z) will be replaced (Just plain Tag will be ignored)

#define MAX_SIZE 80

#define GET_FIELD(a,b) a->b

int ar[MAX_SIZE];

GET_FIELD(point, xCoord);

GET_FIELD(“lalala", f03j?);

int ar[80];

point->xCoord

“lalala”->f03j?

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The #if, and its variants

o #if constant-expression

Include the following block of text if constant-expression is non-zero

o #ifdef Tag

Include the following block if Tag is currently defined (via an earlier #define)

o #ifndef Tag

Include the following block if Tag is currently not defined (via an earlier #define)

o #else

Used to delimit the else clause in a preprocessor if statement

o #elif constant-expression

Used to create an else-if clause in a preprocessor if statement

o #endif

Delimits the end of a preprocessor if statement. There should be exactly one of these for each #if, #ifdef, and #ifndef.


#if examples

#ifdef INCLUDE_DEBUG_PRINT

# define DPRINT(msg) \

fprintf(stderr, “DBG: %s”, msg);

#else

# define DPRINT(msg)

#endif

#ifdef WIN32

# define open _open

# define close _close

#endif

The DPRINT macro when INCLUDE_DEBUG_PRINT is defined, evaluates to printing code. Otherwise, it evaluates to the empty string.

Windows calls the open and close functions, _open, and _close respectively. This is annoying, so let’s fix it with preprocessor macros.


#include

#include essentially copies and pastes the given file into the current line

o There are two forms of #include

o They differ in the order in which directories are search for thegiven file

o The search order is implementation defined

o Here is the general pattern for different compilers:

#include <filename>

�Searches the “include path,” then the current directory

#include “filename”

�Searches the current directory, then the “include path”

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#undef, #error, #warning

o #undef Tag

Removes definition of a Tag. (undoes a #define)

o #error message

Causes compilation to stop at this line with the given error message. Often this is used with #if blocks to indicate an invalid set of #define macros.

o #warning message

Causes the compiler to output an warning at this line with the given message. Can be used as strong reminders that a file needs work.

o #pragma option

Used to pass an option to the compiler. Almost all #pragma commands are compiler-dependent.


#pragma, #line

o #line number

Used to change what line number that the compiler thinks it is on.

This is often seen in:

�Computer Generated Code (from like flex, bison, or something)

�Code outputed by the preprocessor

#line to allows programs to make the compiler’s error messages to correspond to the original source file’s line numbers rather than the generated source file’s line numbers.

Analisis Top Down

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Masalahutama

Sub Masalah A Sub Masalah B Sub Masalah C

Masalah Besar

Sub Masalah A1 Sub Masalah A2

B

A

CA1

A2

Strategi umum dalampenyelesaian masalah besar; kompleks; rumit

Top Down


Contoh Top Down

Mahasiswa Dosen Perkuliahan

Sistem Informasi Akademis

Entry data

Hapus data

Laporan data

Entry data

Hapus data

Laporan data

Entry data

Hapus data

Laporan data


Implementasi : Metode Modular

……..

Call A

……..

Call B

……..

Call C

……..

…….

Call A1

…….

Call A2

……..

…….

…….

…….

…….

…….

…….

…….

…….

A

B

C

A1

A2

Bagian Utama

Dapat diterapkan secara :

- Internal : sub program, procedure, function

- Eksternal : file unit, header, modul

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Sequence/Runtunan


Simple Sequence


Sequence

o Instruksi dikerjakan secara berurutan.

� dari atas ke bawah

Print harga3

harga ← jmlBrg x hrgSat2

input jmlBrg, hrgSat1

Instruksistep

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Contoh Sequence (1)

o Program akan dikerjakan dengan input:

� 2, 1500

Print harga3



Instruksistep

hargahrgSatjmlBrg

OutputVariabelstep


Contoh Sequence (2)

o Mulai dengan langkah-1:

� input 2, 1500

Print harga3



Instruksistep

150021

hargahrgSatjmlBrg

OutputVariabelstep


Contoh Sequence (3)

o Langkah-2:

� Hitung perkalian, simpan hasilnya di variabel

harga

Print harga3



Instruksistep

3000150022

150021

hargahrgSatjmlBrg

OutputVariabelstep

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Contoh Sequence (4)

o Langkah-3:

� Tampilkan isi variabel harga

Print harga3



Instruksistep

30003000150023

3000150022

150021

hargahrgSatjmlBrg

OutputVariabelstep

Input & Output


C-style IO is an acquired taste. Learn to like it.

I/O C-style

Basic functions:

o printf, scanf, fprintf, fscanf, sprintf, sscanf, etc.

o gets, puts, getc, putc, getchar

o read, write, fread, fwrite

We will cover the basics of the “formated” family of

functions (printf, scanf, etc).

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printf(char *format_string, ...);

fprintf(FILE*, char *format_string, ...);

snprintf(char* buf, size_t n, char *format_string, ...);

printf

o In C, all devices are treated like files

o Three standard files are:

� stdin Often the keyboard

� stdout Often the text console

� stderr Often the text console

o printf(....) is fprintf(stdout, ....)

o The format string is a pattern for the output; it describes how to display the arguments to printf.

o Snprintf write to the string “buf”. The variable n specifies the size of the buffer.

o printf returns the number of characters written


format string

o Format strings are normal strings with embedded “conversion specifications” which are placeholders for arguments

o Conversion specifications are a ‘%’ and a letter with an optional set of arguments in between the ‘%’ and letter.

o To print a ‘%’, you need to write ‘%%’

Example:

printf(“Here is a number: %d\n”, 10);

%d is the conversion specification for signed integers.


Conversion Specifications

Conversion Specifications:

o %d, %i -- signed integer

o %u -- unsigned integer

o %f -- floating point number

o %c -- character

o %s -- string

o %x -- hexadecimal value

o %p -- pointer

Converion specifications tell how to translate

a data value into a string

Options:

o l -- long (32-bit value)

o ll -- long long (64-bit value)

o n -- field width of n digits

o .n -- precision of n digits

o 0 -- fill unused field with 0s

There are many more! Read man pages, or Google it.

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printf quiz!

Figure out the output of the following:

o printf(“%.3f rounded to 2 decimals is %.2f\n”, 2.325, 2.325);

o printf(“%d in hex is: %04x\n”, 24, 24);

o printf(“Quizzes are fun, ja?\n”);


scanf(char *format_string, ...);

fscanf(FILE*, char *format_string, ...);

sscanf(char*, char *format_string, ...);

scanf

o scanf(....) is fscanf(stdin, ....)

o All arguments ot scanf must be pointers (or arrays)

o scanf does almost no size checks. It is easy to get a buffer overflow here. Make sure you use a field length specifier with the %s conversion specifer!!!

o scanf returns the number of items read.


scanf Examples

int items_read;

Read a number:

int num;

items_read = scanf(“%d”, &num);

Read a character:

char ch;

items_read = scanf(“%c”, &ch);

Read a string of max length, 79 chars:

char buf[80];

buf[79]=‘\0’; // Ensure a terminating NULL.

items_read = scanf(“%79s”, buf);

Read number after pattern of “a:<num>”:

int num;

items_read = scanf(“a:%d”, &num);

always check the return value of

scanf

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C++-style IO is easier for simple stuff

I/O C++-style

Basic classes:

o iostream (cout, cin, cerr)

o ostringstream, istringstream

cout << “Hello World!” << endll;

cout << “Boo! “ << 10 << ‘c’ << endl;

cerr << “Here’s the error stream” << endl;

int n;

cin >> n;

char ch;

cin >> ch;


...but harder for complex stuff

I/O C++-style continued...

printf(“%.3f rounded to 2 decimals is %.2f\n”, 2.325, 2.325);

…becomes…

cout << setprecision(3) << 2.325

<< “ rounded to 2 decimals is “

<< setprecision(2) << 2.3.25

<< endl;


C and C++ I/O compared

C-style I/O:

• No type safety. What happens with printf(“%d”, ‘c’);?

• Conversion specifications have a high learning curve.

• Almost all the state of the I/O is contained in the function call.

C++ style I/O:

• Manipulators are very verbose/annoying

• Global state gets changed. When you do “cout << 2.4555”, what precision are you set at? You don’t know. It’s worse with threads.

• You get more customizability since C++ I/O is classed based.

NEVER mix C and C++ I/O...until you know what ios::sync_with_stdio() does.

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