Kỹ thuật lập trình hệ cơ điện tử= Programming Engineering in Mechatronics. Chapter II. Modular programming in C++85

❖ Parametrizing functions▪ Using parameters of different types • Arithmetic type parameters The basics of functions... ❖ Parametrizing functions▪ Using parameters of different types • Pa

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KỸ THUẬT LẬP TRÌNH HỆ CƠ ĐIỆN TỬ Programming Engineering in Mechatronic

TRƯỜNG ĐẠI HỌC BÁCH KHOA HÀ NỘI

Giảng viên: TS Nguyễn Thành Hùng

Đơn vị: Bộ môn Cơ điện tử, Viện Cơ khí

Hà Nội, 2020

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Chapter II Modular programming in C++

• Structured programming relies on top-down design

• In C and C++ languages, the smallest structural unit havingindependent functionality is called function

• If functions or a group of functions belonging together are

put in a separate module (source ﬁle), modular

programming is realised

• Structural programming also contributes to creating new

programs from achieved modules (components) by bottom

up design.

• This chapter aims to introduce the modular and procedura

programming in C++.

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❖ The basics of functions

❖ How to use functions on a more professional level?

❖ Preprocessor directives of C++

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The basics of functions

❖ Deﬁning, calling and declaring functions

❖ The return value of functions

❖ Parametrizing functions

❖ Programming with functions

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• In C++, a function is a unit (a subprogram) that has a name and that c

be called from the other parts of a program as many times as it is

needed.

• In order to use a function efﬁciently, some of its inner variables

(parameters) are assigned a value when the function is called

• When a function is called (activated), the values (arguments) to be assigned to each parameter have to be passed in a similar way.

• The called function passes control back to the place where it was calle

by a return statement

• The value of the expression in the return statement is the return

value returned back by the function, which is the result of the function

call expression.

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❖ Defining, calling and declaring functions

• C++ Standard Library provides us many useful predefined functions

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• The general form of a function definition is the following (the

signs 〈 〉 indicate optional parts):

Function definition

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• The steps of calling a function

function_name argument(〈 1 ,argument 2, … argument n〉 )

Steps of calling a function

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• C++ standards require that functions have to be declared before they are called

Function declaration

Function definition

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• The complete declaration of a function (its prototype ):

return_value function_name( parameter declaration list〈 〉 );

return_value function_name( type_list〈 〉 );

declaration C interpretation C++ interpretation type funct(); type funct( ); type funct(void); type funct( ); type funct( ); type funct( ); type funct(void); type funct(void); type funct(void);

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• C++ makes it possible that a parameter list containing at least one parameter should end with three dots ( )

• The transferring (throw) of exceptions to the caller function can be enabled o disabled in function header

return_type function_name parameterlist(〈 〉) 〈throw( type_list )〈 〉 〉

{

〈local deﬁnitions and declarations〉

〈statements〉

return 〈expression ;〉 }

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❖ The return value of functions

• The return_type figuring in the definition/declaration of a function

determines the return type of the function, which can be of any C++ type wi the exception of arrays and functions.

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• By using the type void, we can create functions that do not return any value

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• Functions can return pointers or references

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❖ Parametrizing functions

▪ Parameter passing methods

• Passing parameters by value

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• Passing parameters by value

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• Passing parameters by reference

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▪ Using parameters of different types

• Arithmetic type parameters

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• Arithmetic type parameters

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• User-defined type parameters

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• User-defined type parameters

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• Passing arrays to functions

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• String arguments

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• String arguments

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• Functions as arguments

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• Functions as arguments

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• Variable length argument list

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• Variable length argument list

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• Parameters and return value of the main() function

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Providing command line

arguments

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In a console window In a development environment

C: \C++Book> command1 first 2nd third

C:\C++Book>

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Wrong number of parameters :

command2

Correct number of parameterscommand2 alfa beta

Wrong number of parameters!

Usage: command2 arg1 arg2

Correct number of parameters: argument: alfa 2 argument: bet

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❖ Programming with functions

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▪ Exchanging data between functions using global variables

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• Solution for above example

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• Solution for above example

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▪ Exchanging data between functions using parameters

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▪ Implementing a simple menu driven program structure

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▪ Recursive functions

• greatest common divisor (gcd):

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• binomial numbers:

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How to use functions on a more professional level?

❖ Inline functions

❖ Overloading (redefining) function names

❖ Function templates

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❖ Inline functions

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• Different functions can be defined with the same name and

within the same scope but with a different parameter list

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▪ Creating and using function templates

• A template declaration starts with the keyword template,

followed by the parameters of the template enclosed within the

signs and< >

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▪ Function template instantiation

• A function template can be instantiated in an explicit way as we

if concrete types are provided in the template line containing theheader of the function:

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▪ Function template specialization

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▪ Some further function template examples

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Namespaces and storage classes

❖ Storage classes of variables

❖ Storage classes of functions

❖ Modular programs in C++

❖ Namespaces

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▪ A storage class:

• defines the lifetime or storage duration of a variable,

• determines the place from where the name of a variable can be accessed directly visibility, scope and also determines which– –name designates which variable linkage.–

▪ A storage class (auto register static extern, , , ) can be assigned to variables when they are defined

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▪ Accessibility (scope) and linkage of variables

• In a C++ source code, variables can have one of the following scopes

block

level

A variable of this type is only visible in the block (function block) where it has b defined so its accessibility is local

If a variable is defined on a block level without the storage classes extern and st

it does not have any linkage.

file level

A file level variable is only visible in the module containing its declaration

Identifiers having file level scope are those that are declared outside the function

of the module and that are declared with internal linkage using the static storag class.

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Variable scopes

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▪ Lifetime of variables

• A lifetime is a period of program execution where the given variable exists

static lifetime Identifiers having alifetime static or extern storage class have a static

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▪ Storage classes of block level variables

• Automatic variables: Automatic variables are created when control is passed to their block and they are deleted when that block is exited

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• The register storage class: The register storage class can only beused for automatic local variables and function parameters

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• Local variables with static lifetime

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▪ Storage classes of file level variables

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▪ Storage classes of program level variables

Same definitions (only one of them can

double sum;

double sum = 0;

extern double sum = 0;

extern double sum;

int vector[12];

extern int vector[12] = {0};

extern int vector[];extern int vector[12];extern const int size = 7; extern const int size;

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❖ Namespaces

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Definitions (only one of them can be used) Prototypes

double GeomMean( double a, double b) {

return sqrt(a*b); }

extern double GeomMean(double a,

double b) { return sqrt(a*b); }

double GeomMean( double, double )

extern double GeomMean(double, double);

static double GeomMean(double a, double

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• Accessing the compiled C functions from within C++ source: uthe extern "C" declaration

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❖ Namespaces

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❖ Namespaces

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❖ Namespaces

▪ The default namespaces of C++ and the scope operator

• C++ enclose Standard library elements in the namespace

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❖ Namespaces

▪ The default namespaces of C++ and the scope operator

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❖ Namespaces

▪ Creating and using user-defined namespaces

• Accessing the identifiers of a namespace

Directly by using the scope operator: Or by using the directive using namesp

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❖ Namespaces

• Accessing the identifiers of a namespace

Or by providing using -declarations:

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❖ Namespaces

• Nested namespaces, namespace aliases:

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