C++ Homework Lecture Lab1 代写编程程序

FINM 326: Computing for Finance

Lecture 1: C++ Fundamentals

Programming Environment

The C++ Standard Library: A First Look

Data Types and Operators

Functions

Week 1 Summary

Programming Environment

I We use Visual Studio on Windows as our primary programming environment:

I Most students are familiar with Windows O/S

I Windows can be installed easily on MacBook

I Visual Studio is user friendly and feature rich programming environment

I Free access

I We will also use gcc on Linux as a secondary platform:

I some employers value programming experience on Linux

I another option for those who do not want to use Windows

I You can use one or the other, or both.

I I will use Windows and Visual Studio most of the time.

I I will show how to use gcc and Linux.

I Visual Studio is installed on lab computers. Report issues to Minsik Yu (minsik@uchicago.edu)

Obtaining Software

I Installing Visual Studio (on Windows):

I Instructions are posted on course site

I Mac users:

I may download and install Windows as a second O/S using bootcamp (https://support.apple.com/en-us/HT201468)

I use VMWare (instructions posted on course site)

I Linux access:

I Request a CS account at: https: //account-request.cs.uchicago.edu/account/requests

I Need help? Contact the TAs.

Getting Started with Visual Studio Integrated Development

Environment (IDE)

Getting Started

I Goal is to learn how how to use Visual Studio IDE, to:

1. create a project (application).

2. use the editor to write code.

3. build the application.

4. run the application.

Getting Started: Hello World Program

I We will create a very simple project to illustrate how to use Visual Studio IDE.

I The program shown below writes a message, "Hello, World!", to console (screen):

#include

int main()

{

std::cout << "Hello, World!" << std::endl;

return 0;

}

Our First C++ Project

I Let's code, build and run this program in Visual Studio.

I First, we will learn the steps we need to follow to create a project.

I After that, we will explain this program step by step and learn some C++.

Step by Step

I Step by step instructions used to create an application are illustrated next.

I Start Visual Studio. Select new project.

I Select "Visual C++" -> "Windows Desktop"

I Select "Windows Desktop Wizard"

Enter:

1. (project) name

2. directory location

3. solution name for the project.

I Change Additional Options as follows:

I uncheck Precompiled Header box.

I check Empty Project box.

I We have a new project!

I Now we can to add source les to our project.

I Go to Source Files folder on the Solutions Explorer.

I Right click, and select, Add -> New Item

I Select C++ File

I Name the le appropriately.

I Now you have a blank cpp le.

I Type code.

I Build the project.

I Make sure the project builds successfully.

I Run it.

I You'll see the greeting message on the screen.

Exercise

1. Use the steps shown above to create an application/project.

2. Code Hello World example. NOTE: C++ is case sensitive

3. Build the application.

4. Run it.

5. Change the program to print a di erent message on the screen.

Hello, World Program: Line by Line

int main()

I main is a special function.

I It is the program entry point.

I Every console application we create should have a main function.

I This function returns an integer (int) value.

I We do not pass any arguments to this function.

I Note: We can have two di erent function signatures for main function:

1. int main()

2. int main(int argc, char* argv[]). We will discuss the use of the second function signature later.

I The line below shows the body of our main function.

{

std::cout << "Hello, World!" << std::endl;

return 0;

}

I A function body starts with { and ends with }.

I Body has 2 statements; each statement ends with a semicolon (";").

I First line writes a message, "Hello, World!", to console.

I Here we use some functionality from the C++ Standard Library.

I After that, the function returns 0 (an integer value)¹.

¹We don't have to return a value in main function. Return 0 (zero) is implied.

The C++ Standard Library: A First Look

The C++ Standard Library

I Here, we brie y look at the feature (i.e. to write a message to console) used in the Hello World example.

I The C++ Standard Library implements some very useful features we need.

I The Standard Library is divided into several sections (more precisely headers), based on functionality.

I Each header has a name.

I We need to include the appropriate header in order to have access to its components.

I The functionality to handle output to console is de ned in the iostream header.

I To include it: #include

The Standard Input and Output

I Terminology:

I input: a sequence of byte ow coming into the computer memory from a device (e.g. keyboard, le).

I output: a sequence of byte ow from the memory to an output device (e.g. console, le).

I stream: a sequence of characters (bytes) read from an input device or written to an output device.

I The iostream section of de nes objects to read and write a stream to Standard I/O channels:

I cin

I cout

I and more..

Standard Output

cout (pronounced as see-out):

I known as the standard output

I attached to the standard output device, which usually is the console

I uses the stream insertion operator, << cout << "Hello, World";

Standard Input

cin (we pronounce it as see-in):

I known as the standard input

I attached to the standard input device, which usually is the keyboard

I uses the stream extraction operator ( >>), to read a stream from the standard input

int x; cin >> x;

Namespace

I Namespaces allow us to group classes and functions using a name.

I Functions and classes in the C++ Standard Library are de ned in the std namespace.

I To use them (classes/functions), we have to use the fully quali ed name.

I Example: We saw the use of std::cout.

I std is the namespace.

I :: is the scope resolution operator in C++.

I cout is the object in this case.

I We will see the use of namespaces later, when we discuss classes.

Using Namespaces

I Having to write the namespace every time we use a function is a bit cumbersome.

I There are di erent ways to overcome this problem.

I Technique 1:

using std::cout;

using std::endl;

int main()

{

cout << "Hello, World!" << endl;

}

I Technique 2:

using namespace std;

int main()

{

cout << "Hello, World!" << endl;

}

I If we're not careful, the second technique can lead to subtle problems in large programs.

I I encourage you to use the rst technique.

I I may not show every namespace in subsequent slides after they are introduced.

I E.g. I may show cout without showing using std::cout; but you should assume it is there.

Data Types

I We write programs to handle/manipulate data.

I We use variables to store data.

I Programs need to store di erent kinds/types of data:

I a letter or sequence of letters: e.g. your name

I numbers: e.g. your age

I In C++ every variable has to have a type.

I The type of the variable has to be declared before it is used.

I Once a type is assigned to a variable, it cannot be changed.

I Data types in C++ belong to two main categories:

1. fundamental data types

2. user de ned data types

I Fundamental data types are de ned in the C++ language.

I C++ also allows the user to de ne types (classes).

Fundamental Data Types: Numerical Types

I Numerical values can be whole or real numbers: e.g. 1 or 1.2

I For real numbers we have two types (in C++):

I oat : uses 4 bytes

I double : uses 8 bytes

I As a result, max and min values each can store are di erent.

Type	Size (Bytes)	Value Range

oat	4	3.4	_E 38
double	8	1.7	_E 308

I We can use them to store both negative and positive real numbers.

I For whole numbers we have several types:

I short: uses 2 bytes

I int: uses 4 bytes

I long: at least 4 bytes

I They have signed and unsigned versions:

I unsigned version can store positive numbers only

I signed version can store both positive and negative numbers

Type	Size (Bytes)	Value Range

unsigned short	2	0 to 65,535
short	2	-32,768 to 32,767
unsigned int	4	0 to 4,294,967,295
int	4	-2,147,483,648 to 2,147,483,647

More Types

I Type to hold a ag (true/false)

I bool

I Type to hold a single character

I char

I Reference: https: //msdn.microsoft.com/en-us/library/cc953fe1.aspx

I Type to hold a string of characters

I std::string

I std::string is NOT a fundamental data type

I de ned in the C++ Standard Library

I de ned in the string header le

C++ Operators

Operators for Fundamental Data Types

Listed below are some operators de ned for fundamental types:

I Assignment operator (=) :

a = 5;	//a is an int
b = 1.5f;	//b is a float
c = 1.4;	//c is a	double
d = 'a';	//d s a char
e = true;	//e is a	bool

I Arithmetic operators (+; ; ; =) :

a = a + 1; b = b – 1.2f; c = c * 2.1 ; c = c / 2.2;

I Comparison operators ():

a > 3; a < 3; a >= 3; a <= 3;

Comparison operators return a bool (true/false) value.

I Equality (==): a == 3;

I Non Equality (! =) : a != 3;

I Logical AND (&&) : returns true if both operands are true; returns false otherwise

a == 3 && d == 'a';

I Logical OR (jj) : return true if either or both operands is true; returns false otherwise

a == 3 || d == 'a';

I Modulo % (to nd the remainder from integer division): int x = 7 % 3;

Operators: Short-cuts

We have some short-cuts; e.g. For an int value i:

I Increment:

i++; // same as, i = i+1;

i += 17; // same as, i = i+17;

I Decrement:

i–; // same as, i = i – 1;

i -= 21; // same as, i = i – 21;

I Multiplication:

i *= 13; // same as, i = i*13;

I Division:

i /= 42; // same as, i = i / 42;

Pre x and Post x

I Post x:

I increment x and return old x:

int x = 3; int y = x++;

I now, y == 3 and x == 4

I Pre x:

I increment x and return new value

int x = 3; int y = ++x;

I now, y == 4 and x == 4

Functions

C++ Functions

I We saw the main() function { every application has to have a main().

I We do NOT write the entire program in the main function.

I We use functions and classes.

I It is easier to solve a complex problem by breaking it up into smaller parts.

I And, combine them to solve the problem.

I We write a function to do a certain task or a sub task.

I Combine one/more functions to solve a problem.

I Using functions have several advantages.

I First, let's learn how to write functions in C++.

I Example: we can write a function to display a greeting message on the screen:

void DisplayGreeting()

{

std::cout << "Hello World!" << std::endl;

}

I A C++ function:

I has a name²

I takes zero or more arguments

I usually does something in the function body

I returns some value of a certain type

I if a function does not return anything, its return type is void

²We can also write a function without name

Functions: Example 1

I Our rst function writes the greeting, "Hello World!" to the screen:

#include

void DisplayGreeting()

{

std::cout << "Hello World!" << std::endl;

}

I We can now call this function from the main function:

int main()

{

DisplayGreeting();

return 0;

}

Functions: Example 2

I How would you write a function to add two integers?

int Add(int a, int b)

{

return a+b;

}

int main()

{

int result = Add(2, 3);

cout << " Result :" << result << endl;

}

Functions: Advantages

1. Better/simpler solution: divide the problem into smaller tasks.

2. Better code structure: improve readability/clarity.

3. Reuse: once a function is written, we can use it any number of times.

4. Maintainability: we write a function once, if we want to make a chance, x a bug, we can do it just in one place.

5. Type safety:

I arguments passed to a function should match the types in the function declaration

I program will not compile if there's a mismatch

Parameter Overloading

I Overloading allows 2 or more functions to have the same name:

I they must have di erent input argument types

I they cannot di er by the return type only

I Allows us to write more than one method to do some task in di erent ways, using di erent inputs.

I For example, we can write another Add() function as:

double Add(double a, double b)

{

return a+b;

}

In-Class Exercises

I Write functions to add:

1. two oat values

2. 3 integer values

3. 3 double values

Implicit Type Conversions

I Suppose we have the following function:

double Add(double a, double b)

{

return a+b;

}

I What happens if we use it to add two integer values:

int main()

{

int a = 2; int b = 3;

cout << Add(a, b) << endl;

}

I Question: does this program build?

I Yes, this program builds just ne:

I arguments are passed to the function as doubles

I size of int is 4 bytes; double is 8 bytes

I we can safely store any int value in a double

I C++ (compiler) converts the int to double (implicitly) in this case.

I This is a conversion from a smaller (4 byte) to a larger (8 byte) type.

I It is called a widening, or, promotion

I Promotions are safe implicit conversions.

I Suppose we have the following function:

int Add(int a, int b)

{

return a+b;

}

I What happens if we use it to add two double values:

int main()

{

double a = 2.2; double b = 3.3;

cout << Add(a, b) << endl;

}

I Will this program build?

I Yes, this program also builds:

I arguments are passed as ints

I size of double is 8 bytes; int is 4 bytes

I we cannot safely convert every double value to an int

I C++ (compiler) converts the double do int values implicitly in this case.

I Results in a conversion from a larger (8 byte) to a smaller (4 byte) type.

I It is called a narrowing.

I Narrowing can be dangerous, and results in a build Warning.

I Why is this not an error?

I C++ expects us to know what we're doing

I C++ will let you shoot yourself in the foot if we're not careful

I Lesson: Pay Attention to Build Warnings!

Casting

I What's the result from integer divsion below:

int a = 3, b = 2;

cout << a / b << endl;

I To get the correct (real) number, we must convert at least one operand to real.

I Explicit type conversions are known as casting.

I Casts are not encouraged, sometimes they are necessary.

I C++ supports 4 types of casts (known as named casts).

I We'll look at static_cast now:

I static_cast:

I Used to force conversions, e.g. int->double

int a = 3; int b = 2;

cout << static_cast

I static_cast returns a double value in this case.

Demos

I Implicit type conversions:

I widening

I narrowing

I static cast

I Handling syntax errors:

1. build logs: errors and warnings

2. IntelliSense³: makes coding covenient

I Debugging

3 https://msdn.microsoft.com/en-us/library/dn957937.aspx

C++ and Header Files

I We wrote all code in the same le.

I In practice we never write all code in the same le:

I di cult to read a very large le (with thousands of lines of code)

I doesn't promote reusability

I di cult for multiple programmers to work on the same project

I makes build process longer

I Solution is to use separate les for functions/classes etc.

I This requires using:

I C++ les

I Header les

I Let's illustrate how to implement a function(or related functions) in a separate C++ le.

I Let's use the add functions as an example:

I We will implement the Add() functions in a separate Add.cpp le.

I When we move the add functions to a new le our program won't build.

I The main() function doesn't know about the Add() functions.

I We need to declare a function before we can use it in a separate le.

I We could add the following two declarations before we use them in main:

int Add(int, int);

double Add(double, double);

I This solution is not ideal: it requires us to have these declarations in every le we use them.

I Proper C++ way:

I Write the function declarations in a header le (e.g. Add.h):

int Add(int, int);

double Add(double, double);

I Include it in source les, using #include preprocessor directive:

#include "Add.h"

In-Class Exercise

I Using one (or more) Add() function/functions from the previous exercise, write:

1. function de nition in the header le.

2. function implementation in the cpp source le.

3. call the Add() function from main().

C++ Build Process

C++ build process uses several steps:

1. Preprocessing:

I uses the preprocessor

I the preprocessor handles the preprocessor directives (e.g. #include)

I the output of this step is a C++ le without preprocessor directives

1. Compiling:

I uses the compiler

I checks syntax

I makes sure the data types are compatible with the operations

I each .cpp le is compiled to create an object le (.obj)

2. Linking :

I uses the linker

I creates an executable (.exe) le using the object les

Demo: Build Errors

I We can have build errors in each stage.

I We need to have an idea about each stage to x build problems.

Type Alias

I Type aliasing can help make code:

1. more readable

2. less error prone

I Consider the function declaration below which calculates the

Black Scholes price of an Option.

double BSPrice(double, double, double, double, double);

I Error prone: it is not clear what the arguments are

I We can use typedefs here:

typedef double OptionPrice;

typedef double StockPrice;

typedef double Strike;

typedef double Expiration;

typedef double Rate;

typedef double Volatility;

OptionPrice BSPrice(StockPrice, Strike, Expiration, Rate, Volatility);

The const keyword

I The const keyword is used to de ne a constant value.

I If you try to change the value of a const member, the compiler catches it.

const int MaxValue = 10;

MaxValue = 20; // <= This is an error

I This is another example of the bene ts of type safety in C++.

I We will discuss other uses of the const keyword later in the course.

Comments

I We can write comments using C style or C++ style.

I C style:

/* This is a C style comment */

I C++ style:

// This is a C++ style comment

Assignment 0 (Not Graded)

1. Write a function to add two integers.

2. Read two integer values from the keyboard.

3. Add them using the function you wrote.

4. Write the result to console.

I Individual Assignment.

I Due: January 13, 2018 by midnight (CST).

I Total points: 0 (Zero)

I Submission (Optional):

Clean the solution using Clean Solution under Build tab in Visual Studio.

Compress (zip) the folder containing the project.

Submit on Canvas: follow Assignments -> Assignment 0 link and attach the zip le.

Week 1 Summary

Visual Studio IDE

I We created our rst application:

I we create a project

I solution is a placeholder for one or more projects

I Tools in Visual Studio IDE:

I editor to write code

I intellisense support

I build tools

I debugger

I Build uses 3 steps:

I preprocessing, compiling and linking

I brie y discussed each step

Data Types

I Categories:

1. fundamental

2. user de ned

I We discussed fundamental types and operators

I Compiler can do implicit type conversions:

3. widening/promotion (e.g. int to double)

4. narrowing (e.g. double to int)

I We can force type conversions via casting

Functions

I main(): program entry point

I Write a function to do a certain task or a sub task.

I Combine them to write a large program.

I Functions promote:

I readability

I reusability

I maintainability

I type safety

I You will understand these advantages when we write more code.

C++ Standard Library

I Collection of useful classes/functions.

I Brie y looked at some features in the iostream header:

I streams

I cout

I cin

I Introduced the std::string type in std::string header.

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