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Top Forums Programming sizeof an array of structure without using 'sizeof' operator Post 302302459 by pshaikh on Tuesday 31st of March 2009 04:00:30 AM
Old 03-31-2009
Quote:
But if i try to subtract address of say &array[1] - &array[0] doesn't give the sizeof the array instead it gives 1 always. I just tried printing &array[1] and &array[0] which gives the address. When we subtract the address of begin and end variable it gives the number of bytes occupied between those two and why not in &array[1] - &array[0]. Kindly clarify.
This is because, compiler 'knows' type of array and it places instructions of pointer arithmetic using size of 'type'.

so &array[1] - &array[0] = number of elements of type of 'array' between &array[1] and &array[0]

Try this (char*)&array[1] - (char*)&array[0] or (unsigned long)(&array[1]) - (unsigned long)(&array[0])
 

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KEY(3)									 1								    KEY(3)

key - Fetch a key from an array

SYNOPSIS
mixed key (array &$array) DESCRIPTION
key(3) returns the index element of the current array position. PARAMETERS
o $array - The array. RETURN VALUES
The key(3) function simply returns the key of the array element that's currently being pointed to by the internal pointer. It does not move the pointer in any way. If the internal pointer points beyond the end of the elements list or the array is empty, key(3) returns NULL. EXAMPLES
Example #1 key(3) example <?php $array = array( 'fruit1' => 'apple', 'fruit2' => 'orange', 'fruit3' => 'grape', 'fruit4' => 'apple', 'fruit5' => 'apple'); // this cycle echoes all associative array // key where value equals "apple" while ($fruit_name = current($array)) { if ($fruit_name == 'apple') { echo key($array).'<br />'; } next($array); } ?> The above example will output: fruit1<br /> fruit4<br /> fruit5<br /> SEE ALSO
current(3), next(3). PHP Documentation Group KEY(3)
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