Loops in php -help

gkman · January 8th, 2012, 02:10 PM

hey.

When I was in school we learned to program in java.
the loop formats where very simple to me.

for( initialization; termination; increment)
{
statements;
}

the format in which the for loop is in makes it very easy for me to understand when the loop begins and where it ends.

however I am having a very difficult time understanding the loops in php.

in chapter 2 page 63 there is a for-each loop. it was easy enough for me to understand. the loop was used with an array so I understood that when the array ended so did the loop. the problem for me though was understanding how to do a for-each loop without an array. if I lets say wanted to print 10 times on the screen âhelloâ - how would I go about doing it with a for-each loop? (I don't think that using a while loop is very efficient)

also. in chapter 3 page 93. there is a while loop in the code that prints the query of movies with their movie types. I don't understand the increment of this loop. how does PHP know to move to the next row if there is no statement telling it to like in the example in chapter 2 page 70 (the one that prints the number of movies the user selected) where there was a statement

$numlist = $numlist + 1;

telling the loop to move to the next on the list.

I not sure if I explained my difficulty easily enough to understand

- but Iâm sure that whoever learned java will know what I mean.

please help me.

thanks in advance

UseLess · January 9th, 2012, 04:46 AM

Greetings,

You only use a foreach with an array, if you only wanted to output 'hello' 10 times then you would use a normal for loop like so;

Code:

for($i=0; $i <= 10; $i++)
{
echo 'hello' . "\n";
}

I am guessing here, with regard to the Chapter 3 Page 93 example, but if the while loop is grabbing data from the database with something like:

Code:

while($row = mysql_fetchrow($result))

then the loop counter will come from the database when the next row is obtained.

gkman · January 9th, 2012, 07:24 AM

thanks for the reply.

In your answer you said that the while loop in chapter 3 page 93- changes the row because the end of the row of the database.

the problem is that I want to dictate when the while loop will switch a row in the database (it may sound silly but I'm thinking maybe I will want to have an if argument in the loop that will determine if I want to do a second loop on the same row)

UseLess · January 9th, 2012, 09:53 AM

Greetings,

You could do that as the next row will only be obtained from the db when the current iteration ends. So if you delay the end of the loop to process the current row again then that will work fine, however be careful you do not create an endless loop which will be down to the if condition used to determine if the current row should be processed again.

And I'm not going to ask why you'd want to waste time processing something you've just processed.