Really quick noob question with php:
I'm trying to create a conditional statement where I can check if a variable partially matches a substring.
More specific in my case:
$cal is the name of a file, I want it so if $cal contains ".cfg" it echos some text.
pseudocode:
<?php if ($cal == "*.cfg")
{
echo "Hello ";
}
?>
if (strpos($cal, ".cfg") !== false)
{
echo "some text";
}
EDIT
My proposal for matching exactly "*.cfg":
$cal = "abc.cfgxyz";
$ext = "cfg";
if (strrpos($cal, ".".$ext) === strlen($cal)-strlen($ext)-1)
{
echo "matched";
}
*.cfg, which suggests the OP wanted to test the end of the string.
if (match_extension($filename, $ext)) { ... } instead.
strrpos, strlen and (again) strlen in one line, it's time to consider a regexp. This is really hard to maintain or understand.preg_match can be a reasonable alternative here, unless an "extreme" use leads to the feared performance issue: 10000 iterations on my "EDIT" answer need around 20 milliseconds, and with preg_match 38 ms. Adding 3-4 strlen or strpos simple calls to my answer easily reaches 40 ms (Intel Core 2 Duo 3.16 GHz, 4GB RAM). However, when a simple strpos use is efficient and readable enough, I would prefer it (just for information: 13 ms for my inital answer).In this case, you can simply look at the last four characters of $cal using substr:
if (substr($cal, -4) === '.cfg') {
echo "Hello ";
}
You should look into regular expressions for more complex problems.
if ( preg_match('/\\.cfg$/',$cal) ) echo "Hello ";
should to it. (Assuming you want to match the end of the input string, otherwise, leave out the $)
\.cfg will work because . doesn't need escaping, but technically the backslash needs escaping. (this is just like "$" will contain a literal $, which I think is not something to rely on)preg_match needs to . to be escaped. However, the \ also serves to escape things we put in literal strings. So if we say '\\.' we make a string containing \. which is what we need. So there are two levels of escaping, so to speak.for simple patterns strpos will do nicely.
if (strpos ('.cfg', $string) !== false)
{
// etc
}
For more complicated parterns, you want preg_match, which can compare a string against a regular expression.
if (preg_match ('/.*?\.cfg/', $string))
{
// etc
}
The former offers better performance, but the latter is more flexible.
You can use various approaches here. For example:
$cal = explode('.', $cal);
if(last($cal) === "cfg")) {
echo "Hello";
}
Or using regular expressions (which are probably way slower than using strpos for example):
if(preg_match("/\.cfg$", $cal)) {
echo "Hello";
}
I honestly don't know how the explode() version compares to substr() with a negative value (lonesomeday's answer) or strpos() (which has its flaws, Frosty Z's answer). Probably the substr() version is the fastet, while regular expressions are the slowest possible way to do this).