[Worldforge-all-lists] [WF-Cpptraining] Beginner - Loops

[Jonathan W. <jwi...@ea...>]

Edmund,
With the compiling, I meant just the basics (which is basically what I 
know).  Make
sure to ask questions if needed.  When you are ready to go on to Arrays 
tell me.

There are three main kind of loops:
for statement
while loops
do while loops


**********   For Loops   **********

The for loop/statement is a really powerful tool
for programming.  One of the most common uses for
the for loop is to execute a statement or block
of statements a certain number of times.

Let's say that you want to cout the number 1 through
10 with a new line in between each.  With the for
statement you can do it like so:

for (int x=1; x<=10; x++) cout << x << endl;

The for loop has three parameters.  The first parameter
is the intialization expression (int x=1), the second the
condition (x<=10), and last the iterating expression (x++).

In our example, the for loop notices the intialization
expression first.  Upon executing, a variable x is defined
as being 1.  Then it follows the following loop:
1. Check condition, break out of loop if false
2. Execute the statement or body thereof (cout << x << endl;)
3. Execute the iterator statement (x++, which is the same as x=x+1;)

What if you want a list of numbers starting with 1 and multiplied
by 2 each time (1,2,4,8)?  You can do the following:

for (int x=1; x<=10; x*=2) cout << x << endl;

If you want to execute more than one statement use brackets
like the following:
for (int x=1; x<=10; x*=2)
{
   cout << x << endl;
   // can add more statments
}

********** While Loops **********

A while loop will execute and continue to execute as long as
the condition is true.  The structure is as follows:

while(true) statement;

or

while(true)
{
    statements;
}

********** Do While Loops **********

A do while loop will execute at least once, but after that the
condition has to be true.  The syntax is:

do
{
    statements;
} while(condition);

Here is a program using the do while loop that will
print numbers from 0 to 10:

#include <iostream.h>
int main()
{
    int x = 0;
    do
    {
        cout << x << "\n";
        x++;
    } while (x < 10)

    return 0;
}

-- jw-proph



Edmund wrote:

>> Sorry for not contributing in a while, although I no longer have the
>> motivation
>> I used to to learn new c++ stuff (like with STL) and write lessons.  I
>> am going
> 
> 
> I know what you mean, but not with C++ but with other stuff.  Enthusiasm
> tends to mellow out after a while.  I suppose this goes with the
> territory.  
> 
>> start college this fall, majoring in CS;  that will hopefully get my
>> interest back
> 
> 
> (Or make you completely bored of programming.. *snicker*)  J/king.
> Seriously, good luck with college.  
> 
>> [x] Compiling
>> [ ] "Hello, World!"
>> [ ] Variables, Input
>> [ ] Arithmetic Operations
>> [ ] Conditional Statements
>> [x] Loops (For, Do, While)
>> [x] Arrays
>> [x] Functions
>> [ ] Headers
>> [x] Pointers
>> [x] Pointer Examples
>> [x] Classes
>> [x] Inheritance with Classes
>> 
> 
> My list probably has changed since the beginning; but it's mostly
> because
> I can't remember what I had selected before.   I'm not too sure about
> compiling, since the basic 'gcc -o hello hello.cpp' usually does
> the trick most of the time. 
> 
> Edmund
>