Which one is best and faster method ?(making drop down method) - php

Question

I have two different method which help to make drop_down (select) option. Both are work same. only different is in logic for showing selected option
Method 1:
function unit_type_drop_down($selected=''){
$where = array('status'=>'1');
$unit_type_data = $this->select_result('unit_type', 'id,name', $where);
$html = '';
foreach ($unit_type_data as $value) {
if($value->id == $selected){
$html.='<option value="' . $value->id . '" selected>' . ucfirst($value->name) . '</option>';
}else{
$html.='<option value="' . $value->id . '">' . ucfirst($value->name) . '</option>';
}
}
return $html;
}
Method 2:
function unit_type_drop_down($selected=''){
$where = array('status'=>'1');
$unit_type_data = $this->select_result('unit_type', 'id,name', $where);
$html = '';
foreach ($unit_type_data as $value) {
$html.='<option value="' . $value->id . '">' . ucfirst($value->name) . '</option>';
}
$html = str_replace('value="'.$selected.'"', 'value="'.$selected.'" selected="selected"', $html);
return $html;
}
unit type data has value something like
$unit_type_data = array(
array('id'=>1,'name'=>'unit1'),
array('id'=>1,'name'=>'unit1'),
array('id'=>1,'name'=>'unit1'),
.
.
.
.
.
array('id'=>1,'name'=>'unit1')
);

Answer 1

The first method is faster because IF-ELSE statement and string concatenation consume fewer resources and operations than search and replacement in a string.
Of course, if you want to get exact metrics of speed both methods - should calculate asymptotic complexity for concatenation of strings and replacement string in PHP.
Also, the first method seems more clear to readable than the second method

Answer 2

You can use getusage to check execution time of any PHP script. Or with microtime before and after each script, like this:
$before = microtime(true);
// some script
$after = microtime(true);
echo ($after-$before);