1 / 33

# CMPT 128: Introduction to Computing Science for Engineering Students - PowerPoint PPT Presentation

CMPT 128: Introduction to Computing Science for Engineering Students. Introduction to the basic components of C and C++ programs. Introduction. Computer program : an ordered sequence of instructions whose objective is to accomplish a task .

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

## PowerPoint Slideshow about 'CMPT 128: Introduction to Computing Science for Engineering Students' - ellery

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

### CMPT 128: Introduction to Computing Science for Engineering Students

Introduction to the basic components of

C and C++ programs

• Computer program:an ordered sequence of instructions whose objective is to accomplish a task.

• Programming:process of planning and creating a program

• Programming Language: a set of symbols, special words (semantics), and rules for using those symbols and special words (syntax) to create statements to implement the ordered sequence of instructions to accomplish a task

• When we try to solve a problem using programming we should always begin by breaking the problem into parts.

• Each part describes a process that solves part of the problem (or an object that is part of the problem)

• Each part can be implemented as a function within a program to solve the problem (or a class)

• Programs are divided into smaller modules called functions.

• Functions can

• be separately tested and reused by many programs

• Use other functions

• Be used by other functions

• Become part of libraries

• Every program has a main function.

• The main function controls the highest level of abstraction of the program.

• The main function may call other functions to complete lower level tasks (like evaluating an exponential)

• Many commonly needed functions are supplied in libraries as part of the C and or C++ language, some less commonly needed functions are available as additional add on libraries

• C is a subset of C++

• C codes will run inside a C++ application

• All C libraries are available in C++

• C++ contains many extensions of C

• C++ is object oriented and allows classes

• C++ libraries that are based on classes cannot be used in C

The Components of a Program

• Each C or C++ program includes a series of functions or program units.

• Every C++ application program includes a main function, sometimes called a main program

• There may be other functions used by the main program.

• Functions from C and C++ libraries

• Functions written by the user

• For your first programs we will illustrate only a main function and some functions from libraries

Hello World: your first C++ program

// My first C++ program

// make the computer print Hello world

// connect to any necessary libraries

#include <iostream>

// required, will be explained later in the course

using namespace std;

// the main function, implements the algorithm to solve the problem

// the main function may use functions input an output functions from the iostream

// library. cout is one of these functions.

int main ( )

{

cout << "Hello, world!“ << endl;

return 0;

}

Hello World: your first C program

/* My first C++ program */

/* make the computer print Hello world */

/* connect to any necessary libraries */

#include <stdio.h>

/* the main function, implements the algorithm to solve the problem

the main function may use functions input an output functions from the iostream

library. cout is one of these functions. */

int main ( )

{

fprintf( stdout, “Hello World \n” );

return 0;

}

• Comments are essential to clearly explain the purpose of your code and the methods of implementation used

• When you use another programmer’s code

• When another programmer tries to use your code

• When you try to use your own code after months or years

• Comments make it is much easier to figure out how things work in existing code.

• Do give additional information not obvious from the code

// This program calculates the first 20 primes

• Do not translate code into English

C = A+B

• Comments begin // and end at the end of the line

• Comments can appear on their own line

• // This is a comment

• Comments can appear on the same line as an expression

• A = b + c; // add b to c and store the result in A

// My first C++ program

// make the computer print the string “Hello world”

// connect to any necessary libraries

#include <iostream>

using namespace std;

// the main function, implements the algorithm to solve the problem

// the main function may use functions from included libraries

int main ( )

{

cout << "Hello, world!“ << endl; // Prints Hello world

return 0;

}

• Comments begin /* and end */

• Comments can appear on their own line or on their own block of lines

• /* This is a C comment

it continues until it is closed */

• Comments can appear on the same line as an expression

• A = b + c; /* add b to c, put the result in A */

Hello World: your first C program

/* My first C program */

/* make the computer print Hello world */

/* connect to any necessary libraries */

#include <stdio.h>

/* the main function, implements the algorithm to solve the problem

the main function may use functions input an output functions from the iostream

library. cout is one of these functions. */

int main ( )

{

fprintf( stdout, “Hello World \n” );

return 0;

}

• A main function, or any other function may wish to use functions in the built in libraries of the C or C++ language or in user developed or application libraries

• To use such functions our program must indicate that the libraries are being used and provide a way to access those functions

Hello World: C++

// My first C++ program

// make the computer print the string “Hello world”

// connect to any necessary libraries

#include <iostream> // iostream is a library used to read and write

using namespace std;

// the main function, implements the algorithm to solve the problem

// the main function may use functions from included libraries

// the iostream library includes read and write functions like cout

int main ( )

{

cout << "Hello, world!“ << endl; // Prints Hello world

return 0;

}

• In our first C++ program we are using the iostream library.

• This library is used to read from the keyboard and write to the screen

• Any C++ program that reads or writes information should include the iostream library

• Later we will look at the details of what we can do with this library. (much more)

Hello World: your first C program

/* My first C program */

/* make the computer print Hello world */

/* connect to any necessary libraries */

#include <stdio.h>

/* the main function, implements the algorithm to solve the problem

the main function may use functions input an output functions from the iostream

library. cout is one of these functions. */

int main ( )

{

fprintf( stdout, “Hello World \n” );

return 0;

}

• In our first C program we are using the stdiolibrary.

• This library is used to read from the keyboard and write to the screen

• Any C program must use the stdio library

• Any C++ program may use either the stdiolibrary or the iostream library

Example: Standard Libraries (C,C++_)

• #include <stdio.h>

• The # at the beginning of the line indicates that the command is for the C++ preprocessor (a preprocessor directive)

• The Cor C++preprocessor puts the contents of the file stdio.hinto your program instead of the line of code above then passes the resulting code to the compiler

• If the preprocessor directive to include the library is not part of your program, your program will not be able to use the functions in the library

Using Libraries in C and C++

• A C or C++ program that wants to use libraries starts with one or more include directives

• #include <Library_Reference>

• #include “Library_Reference” //(details later)

• Here Library_Referenceindicates the name of a file containing a list of all the functions in the library.

#include <Library_Reference>

#include “Library_Reference”

• “ “ indicates that the files location should be completely specified by the programmer.

• < > indicates that the file is part of the C or C++ language itself and can be located by the preprocessor, compiler and linker without programmer intervention.

Hello World: C++

// My first C++ program

// make the computer print the string “Hello world”

// connect to any necessary libraries

#include <iostream> // iostream is a library used to read and write

using namespace std; // not needed for C

// the main function, implements the algorithm to solve the problem

// the main function may use functions from included libraries

// the iostream library includes read and write functions like cout

int main ( )

{

cout << "Hello, world!“ << endl; // Prints Hello world

}

using namespace std

• Indicates you wish to use the standard namespace

• In large advanced programs it is possible that you want to use additional namespaces to prevent naming conflicts.

• For this course you will always use the standard namespace and you will always have this line in your programs

Hello World: C++

// My first C++ program

// make the computer print the string “Hello world”

// connect to any necessary libraries

#include <iostream> // iostream is a library used to read and write

using namespace std;

// the main function, implements the algorithm to solve the problem

// the main function may use functions from included libraries

// the iostream library includes read and write functions like cout

int main ( )

{

cout << "Hello, world!“ << endl; // Prints Hello world

return 0;

}

Creating a C or C++ main function

int main ( )

{

Body of the main function

return 0;

}

• The start of the main method is indicated by the statement int main ( )

• The body of the main method (the code that accomplishes the task of the main method) is enclosed in { }.

• The convention used in this course in to put each of the { } on a separate line.

Hello World: C++

// My first C++ program

// make the computer print the string “Hello world”

// connect to any necessary libraries

#include <iostream> // iostream is a library used to read and write

using namespace std;

// the main function, implements the algorithm to solve the problem

// the main function may use functions from included libraries

// the iostream library includes read and write functions like cout

int main ( )

{

cout << "Hello, world!“ << endl; // Prints Hello world

return 0;

}

Body of the C++ program

• For our first program the body consists of a single line of code

cout << "Hello, world!“ << endl;

• cout prints to the screen

• Everything inside the “ “ is printed

• endl means move to the start of the next line before printing anything else

Simple examples of C++ cout

• Print the word OUCH to the screen

cout << “OUCH”;

• Move to the beginning of a new line then print the sum of 6.5 and 3.5 to the screen

cout << endl << 6.5 + 3.5;

Hello World: your first C program

/* My first C program */

/* make the computer print Hello world */

/* connect to any necessary libraries */

#include <stdio.h>

/* the main function, implements the algorithm to solve the problem

the main function may use functions input an output functions from the iostream

library. cout is one of these functions. */

int main ( )

{

fprintf( stdout, “Hello World \n” );

return 0;

}

Body of the C program

• For our first program the body consists of a single line of code

fprintf( stdout, “Hello World \n” );

• fprintfprints to the screen

• Everything inside the “ “ is printed except control characters preceeded by \

• \nmeans move to the start of the next line before printing anything else

Simple examples of C fprintf

• Print the word OUCH to the screen

fprintf( stdout, “OUCH”);

• Move to the beginning of a new line then print the sum of 6.5 and 3.5 to the screen

fprintf( stdout, “\n %f”, 6.5 + 3.5);