How does the break statement work?

[Cogito]

For the first time, I'm attempting to write a small Javascript program
using one on the online reference sites. I need some confirmation as
to the behaviour of the break statement.

In the following code:

for ( row = 0 ; row <= 7 ; row++ ) A <----
{
for ( col = 0 ; col <=7 ; col++ ) B <----
{
if ( check ( row, col ) == "pass" )
break ;
}
}
}

Where will control pass to once the break statement is executed?
Will it continue with the first 'for' statement (A) or the second (B)?

Also my 'check' function needs to pass an indication as to it's
success or failure. It does it by:

return ( "pass" ) ;

Am I doing it correctly?

Any links to useful reference sites would be welcomed.

[RobG]

On Mar 20, 4:33 pm, Cogito <nos...@nospam. nospamwrote:

For the first time, I'm attempting to write a small Javascript program
using one on the online reference sites. I need some confirmation as
to the behaviour of the break statement.

In the following code:

Please indent using 2 spaces in posted code.

>
for ( row = 0 ; row <= 7 ; row++ ) A <----
{
for ( col = 0 ; col <=7 ; col++ ) B <----
{
if ( check ( row, col ) == "pass" )

Syntax error: missing opening { -----------------------------^

Also, check is not defined, row and col should be kept local with var.

break ;
}

alert('Broke to B');

}

alert('Broke to A');

}

Where will control pass to once the break statement is executed?

Fix the syntax error, then try it and see.

Will it continue with the first 'for' statement (A) or the second (B)?

Also my 'check' function needs to pass an indication as to it's
success or failure. It does it by:

return ( "pass" ) ;

Am I doing it correctly?

Why not just return true or false? Then you do:

if (check(row, col)) {
...
}

Any links to useful reference sites would be welcomed.

<URL: http://jibbering.com/faq/index.html >
<URL: http://www.JavascriptToolbox.com/bestpractices/ >
--
Rob

[Cogito]

On 20 Mar 2007 00:16:45 -0700, "RobG" <rg***@iinet.ne t.auwrote:

>Syntax error: missing opening

Thanks for your reply.
Is there a tool to check syntax? I just use notepad to type the
program.

[Cogito]

On 20 Mar 2007 00:16:45 -0700, "RobG" <rg***@iinet.ne t.auwrote:

alert('Broke to A');

Just figured out what alert does. This is a great tool for
debugging!!! Thanks for mrntioning it.

>>
Also my 'check' function needs to pass an indication as to it's
success or failure. It does it by:

return ( "pass" ) ;

Am I doing it correctly?

Why not just return true or false? Then you do:

if (check(row, col)) {
...
}

That looks more elegant. I did not know it.
btw, how would I check for a false condition?

[Tom Cole]

On Mar 20, 5:31 am, Cogito <nos...@nospam. nospamwrote:

On 20 Mar 2007 00:16:45 -0700, "RobG" <[e-mail] .auwrote:

alert('Broke to A');

Just figured out what alert does. This is a great tool for
debugging!!! Thanks for mrntioning it.

Also my 'check' function needs to pass an indication as to it's
success or failure. It does it by:

return ( "pass" ) ;

Am I doing it correctly?

Why not just return true or false? Then you do:

if (check(row, col)) {
...
}

That looks more elegant. I did not know it.
btw, how would I check for a false condition?

A break statement basically tells the code to terminate processing
within the current scope (block). In your case it would only have left
the check block, which is basically useless...

You might try something like:

function checkTable() {
var passed = true;
for (var row = 0; (row < 8 && passed); row++) {
for (var col = 0; (col < 8 && passed); col++) {
if (! check(row, col)) {
passed = false;
}
}
}
return passed;
}

Once the check return fails, no other loops will be processed and the
false condition will be returned. As long as check returns true, the
loops will continue and true will be returned.

Notice that we returned not a string, but a boolean value (true or
false, no quotes). Your check function should do that as well. This
way you can use the returned value in conditional testing AS true or
false as we did in our line

if (! check(row, col)) {

HTH.

[RobG]

On Mar 20, 8:31 pm, Cogito <nos...@nospam. nospamwrote:

On 20 Mar 2007 00:16:45 -0700, "RobG" <[e-mail] .auwrote:

[...]

if (check(row, col)) {
...
}

That looks more elegant. I did not know it.
btw, how would I check for a false condition?

Use the logical NOT operator ! so that false is true and true is
false:

if (!check(row, col)) { ... }

[RobG]

On Mar 20, 11:22 pm, "Tom Cole" <tco...@gmail.c omwrote:
[...]

You might try something like:

function checkTable() {
var passed = true;
for (var row = 0; (row < 8 && passed); row++) {
for (var col = 0; (col < 8 && passed); col++) {
if (! check(row, col)) {
passed = false;
}

Consider replacing the if block with:

passed = !check(row, col);
which leads to the question why the check() function is returning the
opposite of what is required.
--
Rob

[Tim Streater]

In article <4p************ *************** *****@4ax.com>,
Cogito <no****@nospam. nospamwrote:

On 20 Mar 2007 00:16:45 -0700, "RobG" <rg***@iinet.ne t.auwrote:

alert('Broke to A');

Just figured out what alert does. This is a great tool for
debugging!!! Thanks for mrntioning it.

>
Also my 'check' function needs to pass an indication as to it's
success or failure. It does it by:

return ( "pass" ) ;

Am I doing it correctly?

Why not just return true or false? Then you do:

if (check(row, col)) {
...
}

That looks more elegant. I did not know it.
btw, how would I check for a false condition?

Personally I do this:

if (check(row,col) ==true)

or

if (check(row,col) ==false)

as appropriate, being much more readable. All this stuff with:

if (!check(row,col ))

just gives me a headache.

[Dr J R Stockton]

In comp.lang.javas cript message <67vuv2tsvj2vr7 hb4jf0up90b5cla a18gr@4ax.
com>, Tue, 20 Mar 2007 06:33:47, Cogito <no****@nospam. nospamposted:

>
In the following code:

for ( row = 0 ; row <= 7 ; row++ ) A <----
{
for ( col = 0 ; col <=7 ; col++ ) B <----
{
if ( check ( row, col ) == "pass" )
break ;
}
}
}

Where will control pass to once the break statement is executed?
Will it continue with the first 'for' statement (A) or the second (B)?

It will go to B. However, except in javascript of impressive antiquity,
the statement break fred will go to the statement labelled fred:
and likewise for continue fred - the label must be placed
appropriately.

It's a good idea to read the newsgroup c.l.j and its FAQ. See below.

--
(c) John Stockton, Surrey, UK. ?@merlyn.demon. co.uk Turnpike v6.05 IE 6
news:comp.lang. javascript FAQ <URL:http://www.jibbering.c om/faq/index.html>.
<URL:http://www.merlyn.demo n.co.uk/js-index.htmjscr maths, dates, sources.
<URL:http://www.merlyn.demo n.co.uk/TP/BP/Delphi/jscr/&c, FAQ items, links.

[Richard Cornford]

Tom Cole wrote:
<snip>

A break statement basically tells the code to terminate processing
within the current scope (block).

As the units of scoping in javascript are functions not blocks, that is
a misleading assertion. In addition, all looping constructs may use any
statement so not necessarily a block statement, so break does not even
imply exiting a block, just an iteration statement.

In your case it would only have left
the check block, which is basically useless...

You might try something like:

function checkTable() {
var passed = true;
for (var row = 0; (row < 8 && passed); row++) {
for (var col = 0; (col < 8 && passed); col++) {
if (! check(row, col)) {
passed = false;
}
}
}
return passed;

}

<snip>

A ladled break statement would be as effective.

function checkTable(){
var passed = true;
outerLoop: for(var row = 0;row < 8;++row){
for(var col = 0;col < 8;++col){
if(!(passed = check(row, col))){
break outerLoop;
}
}
}
return passed;
}

Richard.