Introduction and basic C++ programming Getting Started

enter your first and last names

you are taken to the exercises

High-level languages are more English-like, easier to code, more costly to run, less flexible. e.g., FORTRAN, BASIC, COBOL, PL/1, ALGOL, APL, Pascal, SIMSCRIPT, Smalltalk, C, C++, Java.

C++ Programming

1. 
   Read data from some input device cin >>
   

2. 
   Write output information onto an output device cout <<
   

3. 
   Perform arithmetic operations + - * /
   

4. 
   Perform relational operations < == >
   

5. 
   Perform logical operations ! && ||
   

6. 
   Branch to a non-sequential instruction (w/wo structure) while
   

7. 
   Store (and retrieve) data values to (and from) memory =
   

Bloodshed Dev-C++ provides an integrated environment for writing programs. "Integrated environment" means Dev-C++ is a combination program, consisting of a text editor and a C++ compiler. A text editor is a limited word processing program that allows you to type in your program, make corrections and changes, and save and retrieve your program from disk storage. The editor is integrated with the Dev-C++ compiler so that you can easily switch between editing your program and compiling and running it. Note that the Dev-C++ compiler allows you to write, compile and run programs in either C or C++.

1. Select File | New | Source file.

3. Right BEFORE the line that says return 0;

 type this:

    system("pause");                  (pause can be lowercase or caps)

This line will keep the output window open when the program has finished executing.

Enter the following program into the program1.cpp file window.

// A First Program in C++

#include

using namespace std;

int main()

{

cout << "Hello. My name is Big Bird.\n";

return 0; //indicates that the program ended successfully

}

4. Save the file by selecting File | Save as , and name the file (something like a1.cpp).

You should get an output window like this:

 6. To print the output,

   a. Right-click in top bar of output window and choose Select All.

   b. Then right-click again and click Copy.

   c. Go back into the editor, select File | New | Source File.

   d. In the new window, right-click and select Paste.

   e. Then use File | Print to print this window.
7. Go to the source file window and select File | Print to print the source file.
8. Click the X in the top right corner to exit the program.
You have just written (OK, typed) and run your first C++ program! (Whew!)

Some Parts of the Program

// hello.cpp

// A First Program in C++

#include

using namespace std;

int main()

{

cout << "Hello. My name is Big Bird.\n";

return 0; //indicates that the program ended successfully

}
(1) comments - At the beginning of each program is a comment, a short description of the problem to be solved. The comment explains the program. The comment is not strictly necessary because a program without it is technically correct. But comments are considered the single most important part of good programming style.
Note that each line of the comment begins with //. Once the symbols // are seen by the C++ compiler, everything to the right is ignored.
(also can have comments that look like this /* */ (if forget last ones what do you think happens?)
(2) Preprocessor directive - Tells the pre-processor to include in the program the contents of the I/O stream header file called iostream.h. This allows us to use standard stream input and output objects like cout (displays to the screen).

Any line in a program that starts with # is an instruction to the compiler, not an actual statement in the C++ language. The line containing #include tells the compiler to allow our program to perform standard input and output operations. Because these operations are so basic, this line of code will appear in all the programs we write.

Every C++ statement must end with a semicolon.

Expression to the right of the operator is inserted (sent) to the cout object (the display screen).

The backslash is an escape character. The character following it takes on a different meaning. eg, \t - tab \a - alert; ring bell

\\ - prints a backslash \” - prints a double quotation mark
(8) return - exits from the function

In this case control over execution is transferred back to the operating system.

Int n;
Variable – a name for a physical location within the computer that can hold one value at a time. (As the name implies, a variable can change its value (e.g. from 4 to 5).

or
int n=66; //declaration can be anywhere in the program

• 
  may use letters, digits, underscores. No spaces.
  
• 
  may not begin with a digit
  
• 
  may be any length but better if less than 31 characters long.
  
• 
  C++ is case sensitive; upper and lower case letters are different.
  
• 
  no reserved words (e.g., const, void, int, …).
  
• 
  Avoid using names beginning with _ (underscore) or __ (double underscore). The C++ compiler uses names like that for special purposes.
  

varname = expr;

8
In C++, double is the primary data type for real numbers. This data type permits decimal places; in addition, it can represent numbers that are extremely large or small. C++ relies on the individual compiler and its implementation on a specific machine to determine the limits of data types. The range of numbers that can be represented by data type int is about five billion; type long int (usually abbreviated as long) has an even larger range of integers.

slash (/). More precisely, a/b means a divided by b. Here are some examples:

In these examples, the result of division, called the quotient, is sometimes an integer and sometimes not. If either (or both) operand is not an integer (e.g., 10.6/2.3, 10.6/2, or even 10/2.0), the division will work as it does in arithmetic, and the quotient will have decimal places. However, if one integer is divided by another, C++ uses integer division to find the quotient. This value is always an integer since any fractional part of the quotient is chopped off.

// Calculates the mean of three numbers.

using namespace std; //need this to drop .h

int main()

{

cout << "First Arithmetic Program" << endl;

cout << (12+5+10)/3 << endl;

system("pause");

return 0;

}
produces this output:

First Arithmetic Program by Big Bird.
9

Press any key to continue . . .
(6) << stream insertion operator

Expression to the right of the operator is inserted (sent) to the screen.

Now, let’s try using a variable to store the mean before printing it.
// This program calculates the mean of three numbers.

// Big Bird learns about variables.

#include

using namespace std;

int main()

{

double mean;

cout << "Second Arithmetic Program by Big Bird.\n\n";

mean = (12+5+10)/3;

cout << mean << endl;

system(“pause”);

return 0;

}
Output:

Try a different set of three numbers. Edit the program and run it again.
// calculates the mean of three numbers.

// Big Bird tries new data.

#include

using namespace std;

int main()

{

double mean;

cout << "Third Arithmetic Program by Big Bird.\n\n";

mean = (11+5+10)/3;

cout << mean <

system(“pause”);

return 0;

}
Third Arithmetic Program by Big Bird.

8

Press any key to continue . . .

OOPS!! What happened? [syntax (compile-time) error vs. run-time error vs. logic (run-time) error]

// calculates the mean of three numbers.

// Big Bird learns that expressions have a type.
#include

using namespace std;

int main()

{

double mean;

cout << "Fourth Arithmetic Program by Big Bird.\n\n";

mean = (11+5+10)/3.0;

cout << mean;

return 0;

} //end main
Output [that’s better!]:
Third Arithmetic Program by Big Bird.
8.66667

Press any key to continue . . .

(C++ Program Phases: …in the C++ programming environment
Edit - Text editor window. Save with .cpp extension
Preprocess - e.g., text replacement, including other library files with the file to be compiled
Compile - to object code
Link - links the object code with the code for the standard library functions referred to in the program. This produces an executable image (with no missing pieces). During Build process
Load - program is placed in memory
Execute - one instruction at a time)