Goodies to Go ™
November 11, 2002–Newsletter #206
This newsletter is part of the internet.com network.
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Featured
this week:
* Goodies Thoughts
– A Smooth Operator
* Q & A Goodies
* News Goodies
* Feedback Goodies
* And Remember This…
Goodies Announcement
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| Goodies Thoughts – |
A Smooth Operator |
There are many types of operators. There are those
who drive cars, those who perform surgery, those who
run casinos, and so on. We don’t care about them,
however (at least not for the purposes of this
newsletter!) On the other hand, we care a lot about
those that add or subtract things from each other,
and in other ways manipulate one thing with another.
I’m talking about the operators in programming
languages; languages like Perl, VBScript and
JavaScript; languages near and dear to a web
developer’s heart!
Since operators are so fundamental to the work of
programming languages, it is important to understand
the types of operator that there are, and their
place in a language. Understanding fundamental
aspects of language structure makes it simpler to
get to know a language you are seeing for the first
time. That being so, a little clarification couldn’t
hurt. I don’t intend to provide a comprehensive list
of either the types of operator or of the operators
themselves, but rather to provide a basic
understanding of the concepts involved.
In a computer language it’s the operators that tell
the computer what to do. If you want to add one to
one to get a result, you would tell the computer
"result equals one plus one". In this example there
are two type of operator at work. "Plus" is an
arithmetic operator that says to add the two numbers
either side of itself together. "Equals" is an
operator that says to assign the value of the answer
to "result".
Not all types of operator are present, or
implemented, in every language. Perl, for example,
has a few special groups of operators that are
peculiar to Perl. Common to most programming
languages, and certainly to those that I have
mentioned here, are arithmetic, assignment,
relational and logical.
Arithmetic operators include the add, subtract,
multiply and divide basic building blocks, along
with exponentiation, modulus and increment.
Hopefully, you are already familiar with the
operation of the first four! It is worth noting that
there are frequently variations on the add and
subtract. In addition to addition, there is also the
"Concatenate" operator. Though concatenate is
usually referred to as a different operator type,
namely a string operator, it is sometimes the same
symbol as add (e.g. "+" in JavaScript). Using
JavaScript for an example, — result = 1 + 1 —
would yield a value of 2 in result, while — result
= "one " + "one" — would yield a value of "one one"
in result.
"Add" adds one number to another, meaning that is
operates on two numbers, or has two operands.
Operators with two operands are called "binary"
operators. Those with one operand are called unary,
and those with three are called ternary. I don’t
know of any operators with more than three operands,
but they might exist in some language.
While subtract is a binary operator, there is also a
unary variation. In its unary form, minus is used to
define a negative number, "-1" for example.
Exponentiation refers to raising a number to a
power. For example (in Perl) 2**4 is equivalent to
2*2*2*2 which yields 16 (2 to the fourth power).
Modulus (a.k.a. Modulo) returns the remainder after
dividing the first operand by the second operand.
For example — result = 7 modulus 3 — would give a
value of 1 in result.
Assignment operands direct a value into a data item.
If our examples above we have shown "equals" as an
assignment operator. Most languages these days,
including the three previously mentioned, assign
from right to left. That is, in the arrangement "op1
= op2" the value already in op2 is assigned to op1,
replacing its value. There are still some languages,
however, that assign from left to right. Cobol is
one such, as in "move op1 to op2" or "add 1 to 1
giving result". By the way, in case you think Cobol
is dead, it’s worth remembering that it is estimated
that there are still more lines of Cobol code in use
today than any other language. Of course, we don’t
really care very much because it’s (probably) never
used for web site development!
Relational operators compare one thing to another.
"Equals" is also a relational operator, as in the
JavaScript example — if op1 == op2 — where you
notice that the language syntax calls for two "="
signs to distinguish it from its assignment cousin.
"Greater than", "less than" and the negatives "not
equal" (etc.), are all examples of relational
operators. Some languages, including Perl, consider
numeric and string relational operator to be
different operator types.
Logical operators include "and", "or" and "not".
These operators are used to combine other conditions
in true/false tests. For an example in JavaScript —
if ((op1 == op2) && (op1 == op3)) — there are two
equality condition tests in the overall condition,
joined by a logical "and". If both test evaluate
true, the overall condition is true, if either or
both evaluate false the overall condition is false.
In a logical "or" the overall condition is true is
either or both evaluate true, and false when both
are false. Be careful with the (unary operator)
logical "not"!! Sometimes it’s simple to see what it
means. For a JavaScript example — if op1 != op2 —
clearly is looking for inequality between op1 and
op2, but consider the Perl example — $op1 = !$op2
— where op1 will be assigned (the "=" assignment
operator) a value of zero if op2 is either null or
equal to zero. Trust me, it can get tricky!
Negatives are like that! Consider: there’s not no
way to misunderstand this!! Beware also of the
bitwise operators (another type) that also include
an "and" an "or" (and a thing called an "exclusive
or") and sometimes a "not". These fellas can also be
tricky to understand and are beyond the scope of
this little piece!
Hopefully, this explanation of this part of computer
language structure will help you to operate on your
own!
Thanks for Reading!
– Vince Barnes
Q
& A Goodies
Questions are taken
from submissions to our Community Mentors. You can ask a Mentor a question by
going to https://www.htmlgoodies.com/mentors/.
Q. But how do I make a link in one
frame change both the main frame and the
sidebar, each going to different pages?
A. There’s a tutorial on just that
subject:
https://www.htmlgoodies.com/tutors/2atonce.html
Q. I want to place the copyright symbol into
a message to be displayed. In HTML you can use
©. What can I use in JavaScript?
A. This is what I have done in the past:
document.write("Copyright ) 2001 – 2002")
Q. I have downloaded a script that is
basically a choice box with a description of the
option selected below the choice box. My problem
is that I want it to target a frame called
"frame1" and Icant seem to find a way to fit
that into the code. Any ideas??
A. Try changing your onClick event to
this: onClick="parent.frame1.location=document.a294.a969.options
[document.a294.a969.selectedIndex].value"
Q. I have a website that can be viewed
nicely in my resolution 1152 x 764 and I want to
be able to do some HTML code that allows me to
keep the page the same size on computers with
all different resolutions so people out there
can view my page the way I have built it.
A. You will have to build your content
into a table and set the table for 790 x auto or
such to accommodate the 800 x 600 window that is
most common.
[You can’t change the resolution of your
visitor’s screen — Ed]
.
Q. I am trying to change the way my text
is displayed on my documents. I understand the
left, center and right alignments. What I am
looking for is a command that allows me to space
my text from the left border to the right
border. In other words I want the left edge of
my text to align left and the right edge of my
text to align right. I have searched but come up
empty handed so far.
A. Try adding align="justify" to the P
tag.
News Goodies
Smaller, Cheaper Pocket PCs on the Horizon
[November 11, 2002] Microsoft and Samsung today
announced a concept design for ‘light and thin’
Pocket PCs that they say will greatly reduce costs
and development time for manufacturers of the
devices.’
Click
here to read the article
AOL Goes After Small Business
[November 11, 2002] SOHOs (small office/home
offices) remain the fastest-growing segment in the
business world. AOL positions to offer them a
ready-made network of marketing and branding
services
Click
here to read the article
Hollywood: Hooray for Broadband!
[November 11, 2002] Major film studios launch the
beta of a download site where you can rent movies;
the questions are how fast it will catch on and
whether it can survive the attack of the Napster
clones.
Click
here to read the article
Gates To Lay Out Future of C++, C#
[November 8, 2002] At the OOPSLA 2002 conference in
Seattle Friday, Microsoft Chairman Bill Gates will
lay out the road map for the Visual C++ .NET and
Visual C# .NET programming languages.
Click
here to read the article
As the Bridex Worm Turns
[November 5, 2002] The Bridex e-mail worm targets a
known vulnerability in Microsoft Windows: it’s
capable of spreading a variant of the active Funlove
virus.
Click
here to read the article
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If you would like to comment on the newsletter or expand/improve on something
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email to this address it may wind up being included in this section of the
newsletter, to be shared with your fellow readers.
Many thanks to all who noticed that a US social
Security number does indeed follow the format
999-99-9999 (three digits, hyphen, two digits,
hyphen four digits) and not 99-999-9999 (two digits,
hyphen, three digits, hyphen, four digits) as we
said in the text. To the gentleman who modified the
script to make it work, you might want to change it
back since it was correct as written – only the text
was wrong!
Top
And
Remember This . . .
On this day in…
1918 World War Ends!
At the 11th hour on the 11th day of the 11th month
of 1918, the Great War ended. The armistice was
signed at 5:00 am on a train at Compihgne, France.
Nine million soldiers were killed in that war.
Another twenty-one million were injured. Germany,
Russia, Austria-Hungary, France, and Great Britain
each lost close to a million or more. World War I
was known as the "war to end all wars" because of
the great slaughter and destruction it caused.
Unfortunately, the peace treaty that officially
ended the conflict — the Treaty of Versailles of
1919 — forced punitive terms on Germany that
destabilized Europe and laid the groundwork for
World War II.
1997 Intel confirms bug
On this day in 1997, Intel confirmed that its
Pentium chips contained a bug that hackers could
exploit to crash computers, and the company released
a fix by the end of the week. The first breed of
Pentium chips, released in 1994, had been plagued by
a bug that produced mathematical errors. After a
public uproar, Intel agreed to replace those faulty
chips with no questions asked
Thanks for reading
Goodies to Go!
