Beginner PHP Tutorial - 48 - String Functions: String Position Part 1 Video Lecture | PHP for Absolute Beginners: From Novice to PHP Master - Web Development

hi this is Alex from PHP academy' back
with another tutorial for the new Boston
now in this video tutorial we're going
to be looking at the function in PHP STR
pause now SCR pause stands for string
positions we've got string here position
and what this function does is it takes
three arguments two are required the
first argument is the string that we
want to search in the second argument is
the keyword or character that we want to
find within the string and the last and
not an optional offset optional argument
is the offset and the offset offset is
where to start from the from within the
string that you're searching so by
default this will be 0 because we know
that arrays or positions start at 0 and
then increment from there so let's say
we have a string here now I'm going to
include a couple of keywords in the
string that we might want to search for
so for example it could be this is a
string and it is an example now I've
included two specific keywords I've
included upwards rather is here and is
here so eventually in this tutorial
we're going to come up with a way where
we can loop through each character of
here as an offset and we can search we
can search through this string for the
position of each of each word so let's
go ahead and we'll test this function
first of all to see if we're achieving
the results that we want and then I'm
going to talk a little bit about how we
can loop to find a few different words
inside so you'll actually notice that
we've got is here so it is within this
we've got is here and we've also got is
here so we've got 3 instances of the
word is so I'm just going to put that
into a variable called find up here for
now so we can use that later on and
we're also going to need the length of
find but I'll tell you why a bit later
so
need to say find length and that is
equal to the string length so we're
bringing in a string or STR Len function
of find so let's test this string
position function so the first argument
we need is the string itself which is
this value here the second we need is
the word to find and that is is so we
can just pop that variable straight into
there the third is it offset which is by
default by zero so we don't need to
include this just yet so now what we can
do is we can echo out the value of this
so let's come into our browser and
refresh and you can see that we've been
given the value two now what's happened
- let's check - what one - and then
that's the start of where this word is
so that's fair enough but what about
this this is here and this is here it's
only going to return the first instance
found after that it's not going to
return every single position so we we
need to find a way to loop somehow and
find this one and return the position
this one and return the position and
this one and return the position so for
example if I was set to set the offset
to let's say 1 2 3 4 - 4 um actually no
0 1 2 3 yep 3 then you'll find that will
return this position here which I think
should be 5 so yet we've returned 5 and
if we start the search site after this
is here so let's say at 10 we get a
value of 25 which is the start of this
is here so you can see that we can use
our offset to our advantage in a loop
then once we found this first is let's
say we found this at position 2 here so
0 1 2 we found this a position - then we
can say well now I want to start
searching two characters after this and
we start the search from whether my
correct is at the moment so here then
once we found our position here we say
well I want to search two characters
after this and then
we carry on the list so we need to we
need to create a loop to do this and
we've seen how string position works
let's get rid of that for now so what we
need to do is we need to create a while
loop and will create the block there now
the essence of the overall idea of this
is that we're going to we're going to
search while we're continually finding
this string so as long as the string is
found we're going to carry on searching
and when it's not found we can break the
loop this is why how our while loop is
now coming into use so inside while I'm
going to create a new variable and
that's going to be called string
position and this is going to be equal
to so remember we can assign variables
values inside of our while loop so we're
constantly reassigning this string
position value that's going to be equal
to string pause now we're going to set
it up exactly the same as before
so our first is the string the string
we're searching and the second is the
word to find thirdly I'm going to create
this variable which I haven't set a
value to yet called offset now the
reason why I'm creating this is because
now when we do find a string inside here
we need to add two to the offset because
we need to add this is two characters
long and that's why I created this find
length here so in actual fact file egg
will be equal to two so whatever we
change this to here we're always going
to be at always updating our search
because we've used functions to keep up
with this so we're looking for is inside
string with a particular offset let's
just give the offset here a value of
zero
before we begin anything