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PHP String Functions
8:59Strings are a major data type for us in PHP and something we will often need to search, parse, & test against. Let's look at some of the most common of the PHP's built-in string functions.
Strings are a major data type for us in
PHP and
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something we'll need to search, parse, and
test against very often.
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Let's look at some of the most common of
PHP's built in string functions.
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The last function that we were looking at
is strlen.
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We were looking at it just to see how we
actually utilize strlen.
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Now, let's go ahead over to Workspaces.
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I'm gonna toggle over and actually use
strlen.
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We're gonna look at a few different string
functions.
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So, mainly they're meant to manipulate or
look into strings.
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They might return something other than a
string such as,
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strlen is going to return integer.
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However, we want to work with strings.
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So, we'll use string functions.
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Let's start by defining a string.
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We will call it phrase.
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And, that phrase will be we only hit what
we aim for.
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All right.
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Going to end that with a semi-colon and
hit save.
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Now, what we want to do is look at our
strlen doc.
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So, it's gonna return to us an integer
value of how long a string is.
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So, we're going to call strlen.
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So, we'll say, strlen, right?
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Let's just make sure that's correct.
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strlen, right.
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And then, our argument that we pass
through, if you look here on the docs,
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is a string.
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So, we have our string, which is phrase,
so we'll pass through phrase.
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Okay.
And then, end it with a semicolon.
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Now, this won't output anything, but it
will run the string length, so
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we'll actually assign that to a variable
and call it $len.
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All right.
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Now, all we have to do is echo that to our
screen.
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So, echo and then len.
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Okay.
Let's switch over and preview this.
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Okay.
And, we get 27.
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So, we have a total of 27 characters in
length, in our string.
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Pretty cool.
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Okay.
So next,
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we're going to take a look at two
different string functions.
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One of them is gonna be sub-string,
S-U-B-S-T-R, and
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the other one is going to be strpos
or string position.
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So, S-T-R-P-O-S.
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So, let's go over and open up a page for
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the docs and find substr and strpos.
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So, we'll go ahead and copy that.
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I'll create a new one here.
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And then, I'm gonna paste in substr,
and it says return part of a string.
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So, you'll see here that in the definition
or
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in the description, we're going to return
part of a string.
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It's going to return to us a string value.
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It's expecting 2 arguments.
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This first argument is string or whatever
string we want to look through.
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The second is a integer value from where
it wants to start.
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So, we can start at the first position or
so
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many positions by character down the
string.
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Then, if you notice in the square
brackets, that means it's optional.
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But, we can pass through an optional length.
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So, let's go ahead and play with this now
inside of WorkSpaces.
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So, we'll do that by go ahead and using
the keyword or the function substr.
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So, S-U-B-S-T-R.
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Then, we're going to pass through the
first argument which is the actual phrase.
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Okay.
And then,
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the second one is where we want to start.
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So, we want to start from a zero based
position, so we'll hit zero.
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And then, we'll go ahead and close this,
and then hit Save.
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And, that's going to start from position
one, and
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it's going to return the entire string.
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So, lets actually echo that out, directly
and see what we get back.
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Just wanna switch back over to our
preview, and then we
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see we only hit what we aim for.
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Now, that's just returning the whole
string.
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But, what if we wanted to start from say,
so many characters in?
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Let's head back over, and we're going to
pass through a second argument, or
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our first argument we're going to change.
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Instead of zero, or the first position,
we'll change it to position five.
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We'll hit save, and go back over and
refresh.
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So now, it says, ly hit what we aim for,
because we started at position five.
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Now, what if we started at position 0, but
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we only wanted to get the first five
characters?
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Well, we can do that too just by simply
passing our third or
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optional argument, which would be in this
case, the numeric 5.
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Switch back over and refresh.
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And now, it says, We on.
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Now, at first glance, you might think,
okay, this is only four characters.
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But, there is a space in between the we
and
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the o, n, so that actually counts as a
character.
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So, a space is technically a character for
us.
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So, we and then space, o, n, is a total of
five characters.
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The next one we wanna look at is string
position.
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So, S-T-R-P-O-S.
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Let's switch back over and look at the
manual and
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we'll go to the search S-T-R-P-O-S.
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Here it is.
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So, this is going to find the first
position or
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the position of the first occurrence of a
sub-string inside of a string.
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So, they've used the keywords here, or
the, the array names to make a little bit
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of sense in the description that says
needle and haystack.
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So, there's a phrase called looking for a
needle in a haystack.
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Well, our haystack is our full string, and
the needle is how we,
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what we want to find.
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So, it's going to be a particular
occurrence,
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using the needle inside of the haystack.
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So, let's take a look at it in code, and
see what we get back.
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Okay?
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So, here we're gonna switch back over to
workspaces, and
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we're going to actually comment out this
line, just for any confusion.
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And then, go echo, and then S-T-R-P-O-S.
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And then, our haystack, which is the first
thing that goes through, is our phrase.
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Then, if you look back over at our
documentation,
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the needle is also required.
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So, we will actually have to pass through
a needle.
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Now, in this case, if you scroll down
here.
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It says if the needle is not a string,
it's then converted to an integer and
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applied as the ordinal value of a
character.
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So, it's expecting that you would put
through a string normally.
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So, you can put through an integer but
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in this case, we're gonna put through a
string.
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So, we're going to put through hit as a
string.
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So, quote H-I-T, and another single quote,
and then hit semi-colon.
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So, we'll save that and switch back over
to our preview.
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Okay.
So, it returned to
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us a integer value of eight.
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So, it's at position eight.
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Let's look at the docs and see what it
means by position.
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So, it's going to return to us a string
position, okay?
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So, it is a string position starting at
zero, not one.
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So, if you notice here it says,
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also note that string positions start at
zero and not one.
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So, for us, when it says eight, that means
that the w on line three is actually zero.
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So, if we count all the way out to the h,
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the h arrives at integer eight in a
zero-based index.
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So, that's how we find it.
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Now, if we were to, say change this to
Bob, and hit save, and
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then we go back and refresh.
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What we're gonna get is nothing, but if we
were to var_dump this instead of
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printing it or instead of echoing it to
the screen, let's see what we get.
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We get a Boolean false.
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If we look at our manual here, we'll
actually see that it
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returns false if the needle was not found,
which is exactly what we were expecting.
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So, we can search for
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a string inside of another string, and get
the position that it starts from.
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And then, return the string starting at
that point or
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do any kind of other functions that we
need with this.
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So, we can actually combine the two
functions we just used.
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So, let's do that now.
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So, here we have echo substr, which is
fine, we're gonna continue to use that,
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but I'm actually gonna move it below here.
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And then, I'm going to do a string
position, but
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I'm going to assign it to a variable called
start.
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And then, I'm going to search for
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a particular phrase, which in our case is
going to be hit, right?
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And then, what I want to do is actually
echo the word
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hit until the end of the sentence.
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So in substring I remove my final
argument.
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And, instead of passing an integer to line
15 as the second argument,
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I'll pass through my variable, which is an
integer value called start.
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Let's save that and go back over to our
page and refresh, and see what we get.
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So now, we get, hit what we aim for, which
is exactly what I was looking for.
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So, you can see by combining two different
string functions in one little bit
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of code we can actually get some very
powerful, powerful results.
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