Search icon CANCEL
Subscription
0
Cart icon
Your Cart (0 item)
Close icon
You have no products in your basket yet
Arrow left icon
Explore Products
Best Sellers
New Releases
Books
Videos
Audiobooks
Learning Hub
Free Learning
Arrow right icon
C++ Fundamentals
C++ Fundamentals

C++ Fundamentals: Hit the ground running with C++, the language that supports tech giants globally

Arrow left icon
Profile Icon Mallia Profile Icon Zoffoli
Arrow right icon
€24.99
Paperback Mar 2019 350 pages 1st Edition
eBook
€8.99 €19.99
Paperback
€24.99
Subscription
Free Trial
Renews at €18.99p/m
Arrow left icon
Profile Icon Mallia Profile Icon Zoffoli
Arrow right icon
€24.99
Paperback Mar 2019 350 pages 1st Edition
eBook
€8.99 €19.99
Paperback
€24.99
Subscription
Free Trial
Renews at €18.99p/m
eBook
€8.99 €19.99
Paperback
€24.99
Subscription
Free Trial
Renews at €18.99p/m

What do you get with Print?

Product feature icon Instant access to your digital eBook copy whilst your Print order is Shipped
Product feature icon Paperback book shipped to your preferred address
Product feature icon Download this book in EPUB and PDF formats
Product feature icon Access this title in our online reader with advanced features
Product feature icon DRM FREE - Read whenever, wherever and however you want
Product feature icon AI Assistant (beta) to help accelerate your learning
OR
Modal Close icon
Payment Processing...
tick Completed

Shipping Address

Billing Address

Shipping Methods
Table of content icon View table of contents Preview book icon Preview Book

C++ Fundamentals

Chapter 2. Functions

Note

Lesson Objectives

By the end of this chapter, you will be able to:

  • Explain what functions are and how to declare them

  • Utilize local and global variables

  • Pass arguments to functions and return values from functions

  • Create overloaded functions and call them appropriately

  • Apply the concept of namespaces in organizing functions

Note

In this chapter, we are going to look at functions in C++, how to use them, and why we would want to use them.

Introduction


Functions are a core tool in a programmer's toolkit for writing maintainable code. The concept of a function is common in almost every programming language. Functions have different names in various languages: procedures, routines, and many more, but they all have two main characteristics in common:

  • They represent a sequence of instructions grouped together.

  • The sequence of instructions is identified by a name, which can be used to refer to the function.

The programmer can call, or invoke a function when the functionalities provided by the function are needed.

When the function is called, the sequence of instructions is executed. The caller can also provide some data to the function to be used in operations within the program. The following are the main advantages of using functions:

  • Reduces repetition: It often occurs that a program needs to repeat the same operations in different parts of the codebase. Functions allow us to write a single implementation that is carefully tested...

Function Declaration and Definition


A function declaration has the role of telling the compiler the name, the parameters, and the return type of a function. After a function has been declared, it can be used in the rest of the program.

The definition of the function specifies what operations a function performs.

A declaration is composed of the type of the returned value, followed by the name of the function and by a list of parameters inside a pair of parentheses. These last two components form the signature of the function. The syntax of a function declaration is as follows:

// Declaration: function without body
return_type function_name( parameter list );

If a function returns nothing, then the type void can be used, and if a function is not expecting any parameters the list can be empty.

Let's look at an example of a function declaration:

void doNothingForNow();

Here, we declared a function named doNothingForNow(), which takes no arguments and returns nothing. After this declaration, we can...

Local and Global Variables


The body of a function is a code block that can contain valid statements, one of which is a variable definition. As we learned in Lesson 1, Getting Started, when such a statement appears, the function declares a local variable.

This is in contrast to global variables, which are the variables that are declared outside of functions (and classes, which we will look at in Lesson 3, Classes).

The difference between a local and a global variable is in the scope in which it is declared, and thus, in who can access it.

Note

Local variables are in the function scope and can only be accessed by the function. On the contrary, global variables can be accessed by any function that can see them.

It is desirable to use local variables over global variables because they enable encapsulation: only the code inside the function body can access and modify the variable, making the variable invisible to the rest of the program. This makes it easy to understand how a variable is used by a...

Passing Arguments and Returning Values


In the Introduction section, we mentioned that the caller can provide some data to the function. This is done by passing arguments to the parameters of the function.

The parameters that a function accept are part of its signature, so we need to specify them in every declaration.

The list of parameters a function can accept is contained in the parentheses after the function name. The parameters in the function parentheses are comma-separated, composed by a type, and optionally an identifier.

For example, a function taking two integer numbers would be declared as follows:

void two_ints(int, int);

If we wanted to give a name to these parameters, a and b respectively, we would write the following:

void two_ints(int a, int b);

Inside its body, the function can access the identifiers defined in the function signature as if they were declared variables. The values of the function parameters are decided when the function is called.

To call a function that takes a parameter...

Working with const References or r-value References


A temporary object cannot be passed as an argument for a reference parameter. To accept temporary parameters, we need to use const references or r-value references. The r-value references are references that are identified by two ampersands, &&, and can only refer to temporary values. We will look at them in more detail in Lesson 4, Generic Programming and Templates.

We need to remember that a pointer is a value that represents the location of an object.

Being a value, it means that when we are accepting a parameter as a pointer, the pointer itself is passed as a value.

This means that the modification of the pointer inside the function is not going to be visible to the caller.

But if we are modifying the object the pointer points to, then the original object is going to be modified:

void modify_pointer(int* pointer) {
  *pointer = 1;
  pointer = 0;
}
int main() {
  int a = 0;
  int* ptr = &a;
  modify_pointer(ptr);
  std::cout ...

Const Parameters and Default Arguments


In the previous chapter, we saw how and when to use references in function parameters and return types. C++ has an additional qualifier, the const qualifier, which can be used independently from the ref-ness (whether the type is a reference or not) of the type.

Let's see how const is used in the various scenarios we investigated when looking at how functions can accept parameters.

Passing by const Value

In pass by value, the function parameter is a value type: when invoked, the argument is copied into the parameter.

This means that regardless of whether const is used in the parameter or not, the calling code cannot see the difference.

The only reason to use const in the function signature is to document to the implementation that it cannot modify such a value.

This is not commonly done, as the biggest value of a function signature is for the caller to understand the contract of calling the function. Because of this, it is rare to see int max(const int, const...

Default Arguments


Another feature C++ provides to make life easier for the caller when it comes to calling functions are default arguments.

Default arguments are added to a function declaration. The syntax is to add an = sign and supply the value of the default argument after the identifier of the parameter of the function. An example of this would be:

int multiply(int multiplied, int multiplier = 1);

The caller of the function can call multiply either with 1 or 2 arguments:

multiply(10); // Returns 10
multiply(10, 2); // Returns 20

When an argument with a default value is omitted, the function uses the default value instead. This is extremely convenient if there are functions with sensible defaults that callers mostly do not want to modify, except in specific cases.

Imagine a function that returns the first word of a string:

char const * firstWord(char const * string, char separator = ' ').

Most of the time, a word is separated by a whitespace character, but a function can decide whether or not...

Namespaces


One of the goals of functions is to better organize our code. To do so, it is important to give meaningful names to them.

For example, in package management software, there might be a function called sort for sorting packages. As you can see, the name is the same as the function that would sort a list of numbers.

C++ has a feature that allows you to avoid these kinds of problems and groups names together: namespaces.

A namespace starts a scope in which all the names declared inside are part of the namespace.

To create a namespace, we use the namespace keyword, followed by the identifier and then the code block:

namespace example_namespace {
  // code goes here
}

To access an identifier inside a namespace, we prepend the name of the namespace to the name of the function.

Namespaces can be nested as well. Simply use the same declaration as before inside the namespace:

namespace parent {
  namespace child {
    // code goes here
  }
}

To access an identifier inside a namespace, you prepend...

Function Overloading


We saw how C++ allows us to write a function that takes parameters either by value or by reference, using const, and organizes them in namespaces.

There is an additional powerful feature of C++ that allows us to give the same name to functions that perform the same conceptual operation on different types: function overloading.

Function overloading is the ability to declare several functions with the same name – that is, if the set of parameters they accept is different.

An example of this is the multiply function. We can imagine this function being defined for integers and floats, or even for vectors and matrices.

If the concept represented by the function is the same, we can provide several functions that accept different kinds of parameters.

When a function is invoked, the compiler looks at all the functions with that name, called the overload set, and picks the function that is the best match for the arguments provided.

The precise rule on how the function is selected is...

Summary


In this chapter, we saw the powerful features C++ offers to implement functions.

We started by discussing why functions are useful and what they can be used for, and then we dove into how to declare and define them.

We analyzed different ways of accepting parameters and returning values, how to make use of local variables, and then explored how to improve the safety and convenience of calling them with const and default arguments.

Finally, we saw how functions can be organized in namespaces and the ability to give the same name to different functions that implement the same concept, making the calling code not have to think about which version to call.

In the next chapter, we will look at how to create classes and how they are used in C++ to make building complex programs easy and safe.

Left arrow icon Right arrow icon

Key benefits

  • Transform your ideas into modern C++ code, with both C++11 and C++17
  • Explore best practices for creating high-performance solutions
  • Understand C++ basics and work with concrete real-world examples

Description

C++ Fundamentals begins by introducing you to the C++ compilation model and syntax. You will then study data types, variable declaration, scope, and control flow statements. With the help of this book, you'll be able to compile fully working C++ code and understand how variables, references, and pointers can be used to manipulate the state of the program. Next, you will explore functions and classes — the features that C++ offers to organize a program — and use them to solve more complex problems. You will also understand common pitfalls and modern best practices, especially the ones that diverge from the C++98 guidelines. As you advance through the chapters, you'll study the advantages of generic programming and write your own templates to make generic algorithms that work with any type. This C++ book will guide you in fully exploiting standard containers and algorithms, understanding how to pick the appropriate one for each problem. By the end of this book, you will not only be able to write efficient code but also be equipped to improve the readability, performance, and maintainability of your programs.

Who is this book for?

If you’re a developer looking to learn a new powerful language or are familiar with C++ but want to update your knowledge with modern paradigms of C++11, C++14, and C++17, this book is for you. To easily understand the concepts in the book, you must be familiar with the basics of programming.

What you will learn

  • C++ compilation model
  • Apply best practices for writing functions and classes
  • Write safe, generic, and efficient code with templates
  • Explore the containers that the C++ standard offers
  • Discover the new features introduced with C++11, C++14, and C++17
  • Get to grips with the core language features of C++
  • Solve complex problems using object-oriented programming in C++
Estimated delivery fee Deliver to Hungary

Premium delivery 7 - 10 business days

€25.95
(Includes tracking information)

Product Details

Country selected
Publication date, Length, Edition, Language, ISBN-13
Publication date : Mar 15, 2019
Length: 350 pages
Edition : 1st
Language : English
ISBN-13 : 9781789801491
Category :
Languages :

What do you get with Print?

Product feature icon Instant access to your digital eBook copy whilst your Print order is Shipped
Product feature icon Paperback book shipped to your preferred address
Product feature icon Download this book in EPUB and PDF formats
Product feature icon Access this title in our online reader with advanced features
Product feature icon DRM FREE - Read whenever, wherever and however you want
Product feature icon AI Assistant (beta) to help accelerate your learning
OR
Modal Close icon
Payment Processing...
tick Completed

Shipping Address

Billing Address

Shipping Methods
Estimated delivery fee Deliver to Hungary

Premium delivery 7 - 10 business days

€25.95
(Includes tracking information)

Product Details

Publication date : Mar 15, 2019
Length: 350 pages
Edition : 1st
Language : English
ISBN-13 : 9781789801491
Category :
Languages :

Packt Subscriptions

See our plans and pricing
Modal Close icon
€18.99 billed monthly
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Simple pricing, no contract
€189.99 billed annually
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just €5 each
Feature tick icon Exclusive print discounts
€264.99 billed in 18 months
Feature tick icon Unlimited access to Packt's library of 7,000+ practical books and videos
Feature tick icon Constantly refreshed with 50+ new titles a month
Feature tick icon Exclusive Early access to books as they're written
Feature tick icon Solve problems while you work with advanced search and reference features
Feature tick icon Offline reading on the mobile app
Feature tick icon Choose a DRM-free eBook or Video every month to keep
Feature tick icon PLUS own as many other DRM-free eBooks or Videos as you like for just €5 each
Feature tick icon Exclusive print discounts

Frequently bought together


Stars icon
Total 108.97
Hands-On System Programming with C++
€41.99
C++ Fundamentals
€24.99
Hands-On Design Patterns with C++
€41.99
Total 108.97 Stars icon
Banner background image

Table of Contents

7 Chapters
Getting Started Chevron down icon Chevron up icon
Functions Chevron down icon Chevron up icon
Classes Chevron down icon Chevron up icon
Generic Programming and Templates Chevron down icon Chevron up icon
Standard Library Containers and Algorithms Chevron down icon Chevron up icon
Object-Oriented Programming Chevron down icon Chevron up icon
Appendix Chevron down icon Chevron up icon
Get free access to Packt library with over 7500+ books and video courses for 7 days!
Start Free Trial

FAQs

What is the delivery time and cost of print book? Chevron down icon Chevron up icon

Shipping Details

USA:

'

Economy: Delivery to most addresses in the US within 10-15 business days

Premium: Trackable Delivery to most addresses in the US within 3-8 business days

UK:

Economy: Delivery to most addresses in the U.K. within 7-9 business days.
Shipments are not trackable

Premium: Trackable delivery to most addresses in the U.K. within 3-4 business days!
Add one extra business day for deliveries to Northern Ireland and Scottish Highlands and islands

EU:

Premium: Trackable delivery to most EU destinations within 4-9 business days.

Australia:

Economy: Can deliver to P. O. Boxes and private residences.
Trackable service with delivery to addresses in Australia only.
Delivery time ranges from 7-9 business days for VIC and 8-10 business days for Interstate metro
Delivery time is up to 15 business days for remote areas of WA, NT & QLD.

Premium: Delivery to addresses in Australia only
Trackable delivery to most P. O. Boxes and private residences in Australia within 4-5 days based on the distance to a destination following dispatch.

India:

Premium: Delivery to most Indian addresses within 5-6 business days

Rest of the World:

Premium: Countries in the American continent: Trackable delivery to most countries within 4-7 business days

Asia:

Premium: Delivery to most Asian addresses within 5-9 business days

Disclaimer:
All orders received before 5 PM U.K time would start printing from the next business day. So the estimated delivery times start from the next day as well. Orders received after 5 PM U.K time (in our internal systems) on a business day or anytime on the weekend will begin printing the second to next business day. For example, an order placed at 11 AM today will begin printing tomorrow, whereas an order placed at 9 PM tonight will begin printing the day after tomorrow.


Unfortunately, due to several restrictions, we are unable to ship to the following countries:

  1. Afghanistan
  2. American Samoa
  3. Belarus
  4. Brunei Darussalam
  5. Central African Republic
  6. The Democratic Republic of Congo
  7. Eritrea
  8. Guinea-bissau
  9. Iran
  10. Lebanon
  11. Libiya Arab Jamahriya
  12. Somalia
  13. Sudan
  14. Russian Federation
  15. Syrian Arab Republic
  16. Ukraine
  17. Venezuela
What is custom duty/charge? Chevron down icon Chevron up icon

Customs duty are charges levied on goods when they cross international borders. It is a tax that is imposed on imported goods. These duties are charged by special authorities and bodies created by local governments and are meant to protect local industries, economies, and businesses.

Do I have to pay customs charges for the print book order? Chevron down icon Chevron up icon

The orders shipped to the countries that are listed under EU27 will not bear custom charges. They are paid by Packt as part of the order.

List of EU27 countries: www.gov.uk/eu-eea:

A custom duty or localized taxes may be applicable on the shipment and would be charged by the recipient country outside of the EU27 which should be paid by the customer and these duties are not included in the shipping charges been charged on the order.

How do I know my custom duty charges? Chevron down icon Chevron up icon

The amount of duty payable varies greatly depending on the imported goods, the country of origin and several other factors like the total invoice amount or dimensions like weight, and other such criteria applicable in your country.

For example:

  • If you live in Mexico, and the declared value of your ordered items is over $ 50, for you to receive a package, you will have to pay additional import tax of 19% which will be $ 9.50 to the courier service.
  • Whereas if you live in Turkey, and the declared value of your ordered items is over € 22, for you to receive a package, you will have to pay additional import tax of 18% which will be € 3.96 to the courier service.
How can I cancel my order? Chevron down icon Chevron up icon

Cancellation Policy for Published Printed Books:

You can cancel any order within 1 hour of placing the order. Simply contact customercare@packt.com with your order details or payment transaction id. If your order has already started the shipment process, we will do our best to stop it. However, if it is already on the way to you then when you receive it, you can contact us at customercare@packt.com using the returns and refund process.

Please understand that Packt Publishing cannot provide refunds or cancel any order except for the cases described in our Return Policy (i.e. Packt Publishing agrees to replace your printed book because it arrives damaged or material defect in book), Packt Publishing will not accept returns.

What is your returns and refunds policy? Chevron down icon Chevron up icon

Return Policy:

We want you to be happy with your purchase from Packtpub.com. We will not hassle you with returning print books to us. If the print book you receive from us is incorrect, damaged, doesn't work or is unacceptably late, please contact Customer Relations Team on customercare@packt.com with the order number and issue details as explained below:

  1. If you ordered (eBook, Video or Print Book) incorrectly or accidentally, please contact Customer Relations Team on customercare@packt.com within one hour of placing the order and we will replace/refund you the item cost.
  2. Sadly, if your eBook or Video file is faulty or a fault occurs during the eBook or Video being made available to you, i.e. during download then you should contact Customer Relations Team within 14 days of purchase on customercare@packt.com who will be able to resolve this issue for you.
  3. You will have a choice of replacement or refund of the problem items.(damaged, defective or incorrect)
  4. Once Customer Care Team confirms that you will be refunded, you should receive the refund within 10 to 12 working days.
  5. If you are only requesting a refund of one book from a multiple order, then we will refund you the appropriate single item.
  6. Where the items were shipped under a free shipping offer, there will be no shipping costs to refund.

On the off chance your printed book arrives damaged, with book material defect, contact our Customer Relation Team on customercare@packt.com within 14 days of receipt of the book with appropriate evidence of damage and we will work with you to secure a replacement copy, if necessary. Please note that each printed book you order from us is individually made by Packt's professional book-printing partner which is on a print-on-demand basis.

What tax is charged? Chevron down icon Chevron up icon

Currently, no tax is charged on the purchase of any print book (subject to change based on the laws and regulations). A localized VAT fee is charged only to our European and UK customers on eBooks, Video and subscriptions that they buy. GST is charged to Indian customers for eBooks and video purchases.

What payment methods can I use? Chevron down icon Chevron up icon

You can pay with the following card types:

  1. Visa Debit
  2. Visa Credit
  3. MasterCard
  4. PayPal
What is the delivery time and cost of print books? Chevron down icon Chevron up icon

Shipping Details

USA:

'

Economy: Delivery to most addresses in the US within 10-15 business days

Premium: Trackable Delivery to most addresses in the US within 3-8 business days

UK:

Economy: Delivery to most addresses in the U.K. within 7-9 business days.
Shipments are not trackable

Premium: Trackable delivery to most addresses in the U.K. within 3-4 business days!
Add one extra business day for deliveries to Northern Ireland and Scottish Highlands and islands

EU:

Premium: Trackable delivery to most EU destinations within 4-9 business days.

Australia:

Economy: Can deliver to P. O. Boxes and private residences.
Trackable service with delivery to addresses in Australia only.
Delivery time ranges from 7-9 business days for VIC and 8-10 business days for Interstate metro
Delivery time is up to 15 business days for remote areas of WA, NT & QLD.

Premium: Delivery to addresses in Australia only
Trackable delivery to most P. O. Boxes and private residences in Australia within 4-5 days based on the distance to a destination following dispatch.

India:

Premium: Delivery to most Indian addresses within 5-6 business days

Rest of the World:

Premium: Countries in the American continent: Trackable delivery to most countries within 4-7 business days

Asia:

Premium: Delivery to most Asian addresses within 5-9 business days

Disclaimer:
All orders received before 5 PM U.K time would start printing from the next business day. So the estimated delivery times start from the next day as well. Orders received after 5 PM U.K time (in our internal systems) on a business day or anytime on the weekend will begin printing the second to next business day. For example, an order placed at 11 AM today will begin printing tomorrow, whereas an order placed at 9 PM tonight will begin printing the day after tomorrow.


Unfortunately, due to several restrictions, we are unable to ship to the following countries:

  1. Afghanistan
  2. American Samoa
  3. Belarus
  4. Brunei Darussalam
  5. Central African Republic
  6. The Democratic Republic of Congo
  7. Eritrea
  8. Guinea-bissau
  9. Iran
  10. Lebanon
  11. Libiya Arab Jamahriya
  12. Somalia
  13. Sudan
  14. Russian Federation
  15. Syrian Arab Republic
  16. Ukraine
  17. Venezuela