namespace std

          As for the include namespace std; (pictured right). This allows you, the code writer, to be able to group classes, functions, and Objects all under different modular code structures. In other words, this allows the program to be devided into different "sections" making it both easier to read as well as to program. So, instead of all the code having to be in one area, it can be split up into multiple areas. For more indepth infomation go to cplusplus.com

How Variable Types Interact

          The way in which variables react with eachother vary, depending upon how you put them together. For example a Integer that is added, multaplied, or devided, by another Integer, will always end with a integer value. For example 2+2 will be the integer 4. 3 devided by 2 will be the integer value of 1. Doubles are the same. If you add 1.1 + 1.1 you get 2.2. If you multiply 2.2 by 2.2 then you will get 4.84, and finally if you divide 2 by 3 then you get .66666 repating. Now if you take a Integer added or multplied by a double then that integer is turned into a double, and thus the variable type must be able to hold the change. For example if you have int someInt = 1; and you have double someDouble = 1.1; and you take these two and add them together, a double variable is needed in order to hold the outcome, becuase 1 + 1.1 (a int + a double) = 2.1 (a double). There is also a type of variable called a char that is used to represent a letter. Though there purpose is to represent a letter, you need to note that letters, in c++, are represented by ASCII charcters, which means that every letter has a corrosponding number, this means that they can not be easily compared to other "Strings," which is a more advanced data type.

Go here see more examples and see further explanations on Variable Interactions. Examples of chars will be shown later on.

LOOPS

          In progamming you may need to print data out over and over again to show changes in data. This becomes very tedious if you had to use a cout every time you wanted to print something. In order to fix this we have loops. Loops allow you to print data out many times over with only a few lines of code. There are a couple different kinds of loops: while, for, and do-while. A while loop executes "While something is true," and is also known as a "pre-test loop." The syntax for a while loop is, while(condition). A for loop is used when you know how many times the loop needs to execute, for example if you want to print out a statement so many times. The syntax for a for loop is, for(counting variable; condition; incrament counting variable). The final loop is the do-while loop which is a Post-test loop, which means that the loop will execute at least once before the conditions are checked. The syntax for the do-while loop is, do{code} while(condition); . Keep in mind that all of the operators that you can use in a if statement you can use in a loop. There are also operations, or key words, that will allow you to break out of a loop entirely or just break out one iteration of it if you wish. These key words are break, and continue. Break will take you completely out of the loop, while continue will skip one iteration of the loop.

Go here see more examples and see further explanations on Loops.

ADVANCED FUNCTION FEATURES

          Functions are great if you want to send data to them and have a value returned, but what if you want to change the value of a variable that already exists? Or make a variable visible to all functions in the program? Functions infact do allow you to do this in a few very simple ways. If you want to change the actual variable then all you have to do is put the & symbole infront of the variable name on the top. Example: void increase(int amount, int &toBeIncreased). Variables are also known as Local or global. Local variables are only visible inside of the function that they are defined in. While Global variables are visible to all functions within the program. Global variables are often defined right below the include statements. Variables also have what is called Scope. Scope is where a varible is variable is useable, that is, the specific area in which a variable can be used and seen by a loop, function, or the program itself. A for loop is a good example of this. When you inetate the counter (ie int i=0;), that variable is only useable inside of that loop, and if you declare another variable inside of the loop, then that varaible is only useable from where it was declared to where the for loop ends.

          Functions also allow you to declare Static Local Variables. These static variables allow the function to hold the current value of a variable though different function calls. For example, if you have a variable count that is used to keep track of how many times a function is called, then you don't want the variable to reset everytime the function is called. To avoid this you declare it as static int count=0; which keeps the variable's current value even after the function code is completed. So if count is increased by 1 everytime the function is called then on the next call count will equal one, on the second call count will equal two and so on. Keep in mind that the static variable IS ONLY VISIBLE(a.k.a it's Scope) to the function in which it was declared in.

          Finaly, what if you, the programmer, still wants a function to run even if the user dosen't enter any infomation or your program while it is running dose dosen't have the correct infomation? Well you can add in what is called "Default Arguments." What Default Arguments allow the programmer to "pre-set" values for parmeters in a function. In order to do this just add a equal sign after the parameter and place in the default number that you want it to be. The header would look like this: void cirArea(double r=1). With this default value, if the user enters a value then it over writes the default, but if the user enters nothing, then the default value is used. If you do not want to give one parameter a defulat value because eather you know it is value that is comming from another part of the program that the user dose not affect, or you know it will have a value everytime, then these variables are declared just like a normal parameter would be. The only catch is, any variables that do not have a defulat value need to be placed as the first parameters. For example: void doSomething(int x, int y=2, int z=4). Remember that you are allowed to set the default values to whatever you want/need them to be.

Go here see more examples and see further explanations on Advanced Function Features.

Objects and Classes

          Though there was a lot learned above, that alone is not enough information to be able to program large complicated programs. In order to produce large and redundant programs you need Object-oriented programming (OOP). OOP is programming with objects. Objects represent entities in the real world such a student, circle, etc. Classes help you do this, classes use variables in order define objects such as circles, and with the class you can retrieve, access, print out, and change any information you want. The way you define a class is: class className (i.e circle). Then right below that there are curly braces ({}) and the last one is followed by a semicolon (; unlike functions). Next you want to add inside whether or not the functions are public or private. At least for now, most of the time you are going to make the class public. Pubic means that the variables and functions inside of the class are all visible by the rest of the program. While private means that the variables below it can only be seen and used inside of the class. All you need to do in order to use public or private, just be inside of the curly braces of the class and put: "public:" or "private:" and everything right below that will be either public or private. The next important part of a class is the Constructor which allows you to inmate the class as well as sends it the initial information to start using it. Constructors have three basic rules that need to follow: 1) The constructor is the same name as the class. 2) They have no return type, just there name. 3) They are involved when the object is created; they play the role of initializing objects. Inside of that constructor you need to set the parameters that are passed to the constructor to the global variables inside of the class so that you will be able to use them. There can also be multiple constructors, each one accepting different parameters, a lot like a function. After you complete your constructor you can create your class functions, the same way you would create functions above you main, except for they are inside of the curly braces of the class.

          Once you have your class created it is very easy to call and use that class inside of the main. So for example, if the class is called circle all you have to put is: class name (i.e Circle) what you call the class in the main (i.e circle1)(parameters); Calling class functions looks like this: name of class in main (i.e circle1).class function name (i.e area)(parameters);

Go here see more examples and see further explanations on Objects and Classes.

This is in no way all you can do with classes, this is mearly a simple introduction to classes and how they can be used, and to help understand them a little better.

The String Class

          The String Class allows the user to do many different tasks with string literals and C-strings. The best way to think of Strings is to think of them as an Array of characters with what is called a "null terminator ('\0')." This tells the computer that this is the end of the of the C-string and to stop at that location in the Array. It is very easy to declare an empty string, much like declaring a empty int or double just put: string s1; C++ uses the no-arg constructor (no argument) to make an empty string. The programmer may then use the the class function: string message('string literal'); Inside of the () you can place a word or sentence. The programmer may also assign a word or sentece to the string by simply putting: s1="what the user wants"; The programmer may also Append to strings, whether it be in the middle of the already created string, end of the string or even the beginning. The programmer may also want to print out or grab a specific letter out of string litteral. The programmer can use the stringVarName.at(index); *Note that the first letter of the word/sentence will be index 0. The programmer may also get the size, capacity, and c_str() of a string. Their are many other functions the programmer can preform on strings, they are all listed on the explanation page.

The string class has string operators that can be used to compare and edit string variables. Their is the equal sign (=) which allows the programmer to assgin a string to a string variable. The plus sign (+) will allow the programmer to add to a string, they may also use the plus equal (+=) to add to a string variable. The programmer may also use the brackets ([]) to access a char at a specific index. << allows the programmer to place a string into a stream, such as the output stream, and can use >> to extract a string from the stream, such as when a user inputs their name. The string class also allows the programmer to compare strings the same way as comparing intergers. I personally was taught not to use these, but they are: ==, !=, <, <=, >= , and >.

Pointers

          Points are the heart and soul of C++, they allow you to use dynamic memory, that can greatly improve the effectiveness of your programs. With pointers though you have to be very careful with what you are doing with them. For example, if you delete a pointer and you delete the pointer, but not the data it is pointing to, you then have what is called a MEMORY LEAK. Although the OSs garbage collection should handle the bits that are left over, there is a possibility that it won't and could do serious damage to the computer, or even cause another one of your programs to do something you really don't want it to do. A golden rule is, if your done with the memory the pointer is pointing at erase DELETE that section of memory. You also have to use the BIG 3, shown on linked page, that you must include in your class if you use dynamic memory. There is too much detail to go into on this page, so please refer to the Pointers pages.

Operator Overloading

          Operator Overloading allows the programmer to tell the program what he/she wants it to do in a specific situation. For example, you can define how the + sign will affect your class. So lets say your class has a list of items in it, you could the + sign all all the values of both lists to a new list and return the new list inside of a class, complicated right? I'll show more examples on the following page, Operator Overloading.