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Diterbitkan olehHartono Widjaja Telah diubah "8 tahun yang lalu
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Pemrograman Berbasis Objek Johannes Simatupang, MKom, Cobit5 NIDN : 0318017001 www.opensolusi.info Pertemuan-4 Versi 2.0.1
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Pokok Bahasan / Sub Pokok Bahasan Pertemuan-4
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Modularity Programming (1): Function Concept Functions membagi program ke dlm komponen program (modularisasi program) agar mudah di di-manage Modules: functions dan classes Programs dapat mengunakan modul baru dan “prepackaged” modules Modul baru: programmer-defined functions, classes Prepackaged: dari standard library (mis. Library Math) Functions dipanggil oleh function call Berupa function name dan argument Analogy: Boss ke anak buah Boss (calling function or caller) minta anak buahnya (called function) untuk melakukan task dan melaporkan (return) hasilnya. [A] Hal 162-166
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Modularity Programming (2): Function Definition Format function definition return-value-type function-name ( parameter-list ) { declarations and statements } Return-value-type ▪ Data type hasil return ( void if nothing to returned) Parameter list ▪ Deklarasi variable lokal yg dipisahkan oleh koma yg dikirim ke function ▪ Untuk mendapatkan informasi dari luar function ▪ If no arguments, use void or leave blank [A] Hal 162-166
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Modularity Programming (3): Function Prototype Memberitahukan compiler tentang tipe argument dan return type function int square( int ); Detail definisi fungsi ditulis nanti Function prototype berisi Function name Parameters Return type ( void if return nothing) [A] Hal 162-166
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Modularity Programming (4): Function Prototype Function Prototype harus sama dengan function definition Function prototype double maximum( double, double, double ); Function Definition double maximum( double x, double y, double z ) { … } Function signature Adalah nama dan parameter function ▪ double maximum( double, double, double ); Function signature [A] Hal 162-170
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Modularity Programming (5): Contoh Function Function Prototype Call Function Function Definition
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Argumen Coercion Arguments dapat memaksa type tertentu ▪ Converting int (4) to double (4.0) cout << sqrt(4) Aturan konversi ▪ Argument secara otomatis di-convert ▪ Mengubah double menjadi int dapat memotong data 3.4 menjadi 3 ▪ Mixed type menjadi highest type (promotion) Int * double double
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Header Files Header files berisi Function prototypes Definisi data types dan constant Header files berakhiran.h Programmer-defined header files #include “myheader.h” Library header files #include
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Recursion Recursive functions Functions that call themselves Hanya dapat menyelesaikan base case Jika tidak base case Pecahkan problem ke dalam smaller problems Buat function baru yg bekerja di smaller problem (recursive call/recursive step) ▪ Slowly converges towards base case ▪ Function makes call to itself inside the return statement
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Contoh Recursion : Faktorial n! = n * ( n – 1 ) * ( n – 2 ) * … * 1 Recursive relationship n! = n * ( n – 1 )! 5! = 5 * 4! 4! = 4 * 3!… Base case 1! = 0! = 1 unsigned long factorial( unsigned long number ) { if ( number <= 1 ) // base case return 1; else return number * factorial( number - 1 ); }
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Contoh Recursion : Deret Fibonacci Deret Fibonacci fib(n) = fib(n-1) + fib(n-2) 0, 1, 1, 2, 3, 5, 8... C++ code for Fibonacci function long fibonacci( long n ) { if ( n == 0 || n == 1 ) // base case return n; else return fibonacci( n - 1 ) + fibonacci( n – 2 ); }
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Recursion vs. Iteration Repetition Iteration: explicit loop Recursion: repeated function calls Termination Iteration: loop condition fails Recursion: base case recognized Keduanya melakukan pengulangan / looping
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Inline Function Inline functions Keyword inline before function Asks the compiler to copy code into program instead of making function call ▪ Reduce function-call overhead ▪ Compiler can ignore inline Good for small and often-used functions Example inline double cube( const double s ) { return s * s * s; } const tells compiler that function does not modify s [A] Hal 195-166
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Ilustrasi Inline Code
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Contoh Inline Function #include const float Pi = 3.1415926; inline float area(const float r) {return Pi * r * r;} main() { float radius; std::cout << "Enter the radius of a circle: "; std::cin >> radius; std::cout << "The area is " << area(radius) << "\n"; return 0; }
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Call Function Type Call by value Copy of data passed to function Changes to copy do not change original Prevent unwanted side effects Call by reference Function can directly access data Changes affect original Call by Pointer copies the address of an argument into the formal parameter Changes affect original [A] Hal 167-170
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Ilustrasi Passing By Value
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Passing Argument to Functions (1): Byvalue Constant
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Passing Argument to Functions (2): By Value Variable
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Reference parameter Reference parameter Alias for argument in function call ▪ Passes parameter by reference Use & after data type in prototype ▪ void myFunction( int &data ) ▪ Read “ data is a reference to an int ” Function call format the same ▪ However, original can now be changed [A] Hal 182-185
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Ilustrasi Reference Parameter
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Contoh Call By Reference
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Function Overloading Function overloading Functions with same name and different parameters Should perform similar tasks ▪ I.e., function to square int s and function to square float s int square( int x) {return x * x;} float square(float x) { return x * x; } Overloaded functions dibedakan oleh signature Based on name and parameter types (order matters) Name mangling ▪ Encodes function identifier with parameters Type-safe linkage ▪ Ensures proper overloaded function called [A] Hal 188-190
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Default Arguments Function call with omitted parameters If not enough parameters, rightmost go to their defaults Default values ▪ Can be constants, global variables, or function calls Set defaults in function prototype int myFunction( int x = 1, int y = 2, int z = 3 ); myFunction(3) ▪ x = 3, y and z get defaults (rightmost) myFunction(3, 5) ▪ x = 3, y = 5 and z gets default [A] Hal 197-198
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