substr() is not working as expected

问题

I am just trying to extract the date's year, month and day separately so that I can use it as per my wish.

I stored the current date in $today and used substr() to extract the strings from it. But I am getting some strange behaviour from what I am doing.

My current code:

$today = date("Y/m/d");

$_year = substr($today, 0,4);
$_month = substr($today, 5,7);
$_day = substr($today, 8, 10);

echo $_year . " " . $_month;

The $_year works correctly as expected but the problem arises from $_month, no matter what position I start my substr() the month and day gets paired up with each other.

Can anyone help me solve this issue? It's driving me crazy.

回答1:

You should have a look at substr reference: http://php.net/manual/it/function.substr.php

That function accepts 3 parameters: $length is the length of the string you want to cut starting from $start

string substr ( string $string , int $start [, int $length ] )

In your case, this will work properly:

$today = date("Y/m/d");
$_year = substr($today, 0,4);
$_month = substr($today, 5,2);
$_day = substr($today, 8, 2);
echo $_year." ".$_month;

回答2:

This should work for you:

Just explode() your date by a slash and then use a list() to assign the variables.

list($year, $month, $day) = explode("/", $today);

回答3:

Just use:

echo date("Y m");

If you want to have every part of the date in an individual variable, I highly encourage you to use the DateTime class:

$dt = new DateTime();
$year = $dt->format('Y');
$month = $dt->format('m');
$day = $dt->format('d');

echo $dt->format('Y m');

回答4:

$today = date("Y/m/d");
$_year = substr($today, 0,4);
$_month = substr($today, 5,7);
$_day = substr($today, 8, 10);
echo $_year." ".$_month;

should be

$today = date("Y/m/d");
$_year = substr($today, 0,4);
$_month = substr($today, 5,2);
$_day = substr($today, 8, 2);
echo $_year." ".$_month;

回答5:

You can use it as

$today = date("Y/m/d");
$today = explode("/", $today);
$year = $today[0];
$month = $today[1]; 
$day = $today[2];
echo $year . ' ' . $month .' '. $day; // 2015 05 05

回答6:

substr() doesn't work asyou think
You're thinking of : string substr ( string $string , int $start , int $end )
But it is : string substr ( string $string , int $start , [int $length)

So use substr($today,5,2) for month and substr($today,7,2) for day

来源：https://stackoverflow.com/questions/30051238/substr-is-not-working-as-expected