Sesi03 Input Output n Sequence

Analisis Top Down input & Output Runtunan Pertemuan 3

Overview o o o o o o o

Deskripsi Tujuan Instruksional Referensi Overview Library Header Analisa Top Down Input & Output Runtunan

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Deskripsi Pada pertemuan ini akan dipelajari mengenai Analisa 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

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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 dan 21) 3. Herianto,“Presentasi Pemrograman Terstruktur.ppt”,2004

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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) IF-UTAMA

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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 ‘;’. IF-UTAMA

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#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[80]; point->xCoord “lalala”->f03j?

int ar[MAX_SIZE]; GET_FIELD(point, xCoord); GET_FIELD(“lalala", f03j?); IF-UTAMA

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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-UTAMA

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#if examples The DPRINT macro when INCLUDE_DEBUG_PRINT is defined, evaluates to printing code. Otherwise, it evaluates to the empty string. #ifdef INCLUDE_DEBUG_PRINT # define DPRINT(msg) \ fprintf(stderr, “DBG: %s”, msg); #else # define DPRINT(msg) #endif Windows calls the open and close functions, _open, and _close respectively. This is annoying, so let’s fix it with preprocessor macros. #ifdef WIN32 # define open _open # define close _close #endif IF-UTAMA

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#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 the given file o The search order is implementation defined o Here is the general pattern for different compilers: #include Searches the “include path,” then the current directory #include “filename” Searches the current directory, then the “include path” IF-UTAMA

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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.

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#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.

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Analisis Top Down

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Top Down Masalah Besar

Sub Masalah A

Sub Masalah A1

Sub Masalah B

Sub Masalah C

Sub Masalah A2

Masalah utama

B

C A1

A A2

Strategi umum dalam penyelesaian masalah besar; kompleks; rumit IF-UTAMA

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Contoh Top Down Sistem Informasi Akademis

Mahasiswa

Perkuliahan

Dosen

Entry data

Entry data

Entry data

Hapus data

Hapus data

Hapus data

Laporan data

Laporan data

Laporan data

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Implementasi : Metode Modular Bagian Utama …….. Call A ……..

A

A1

……. Call A1 …….

……. …….

Call A2 ……..

B Call B ……..

A2

……. …….

……. …….

C

Call C ……..

……. …….

Dapat diterapkan secara : - Internal : sub program, procedure, function - Eksternal : file unit, header, modul

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Sequence/Runtunan

Simple Sequence

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Sequence o Instruksi dikerjakan secara berurutan.
dari atas ke bawah step

1

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Instruksi

input jmlBrg, hrgSat

2

harga ← jmlBrg x hrgSat

3

Print harga

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Contoh Sequence (1) o Program akan dikerjakan dengan input:
2, 1500 step

Instruksi

1

input jmlBrg, hrgSat

2

harga ← jmlBrg x hrgSat

3

Print harga

step

Variabel jmlBrg

hrgSat

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Output harga

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Contoh Sequence (2) o Mulai dengan langkah-1:
input 2, 1500 step

Instruksi

1

input jmlBrg, hrgSat

2

harga ← jmlBrg x hrgSat

3

Print harga

step 1

Variabel jmlBrg

hrgSat

2

1500

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Output harga

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Contoh Sequence (3) o Langkah-2:
Hitung perkalian, simpan hasilnya di variabel harga step

Instruksi

1

input jmlBrg, hrgSat

2

harga ← jmlBrg x hrgSat

3

Print harga

step

IF-UTAMA

Variabel jmlBrg

hrgSat

1

2

1500

2

2

1500

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Output harga

3000

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Contoh Sequence (4) o Langkah-3:
Tampilkan isi variabel harga step

Instruksi

1

input jmlBrg, hrgSat

2

harga ← jmlBrg x hrgSat

3

Print harga

step

Variabel jmlBrg

hrgSat

Output harga

1

2

1500

2

2

1500

3000

3

2

1500

3000

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3000

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Input & Output

I/O C-style C-style IO is an acquired taste. Learn to like it. 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 printf(char *format_string, ...); fprintf(FILE*, char *format_string, ...); snprintf(char* buf, size_t n, char *format_string, ...); 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 IF-UTAMA

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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.

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Conversion Specifications Converion specifications tell how to translate a data value into a string 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

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”);

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

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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);

always check the return value of scanf

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:”: int num; items_read = scanf(“a:%d”, &num);

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I/O C++-style C++-style IO is easier for simple stuff Basic classes: o iostream (cout, cin, cerr) o ostringstream, istringstream cout