Code:
code
$myVar="abCd";

$myVar1 = str_replace('a','A', $myVar)

echo $myVar1;

result

AbCd
The code above replaces the first letter of $myVar which is small letter "a" to the big letter "A".
The result is what I wanted when I knew the first letter is "a".
But How can I change it when I don't know it?


If it is "a", I like to change it "A".
If it is "b", I like to change it "B".
If it is "c", I like to change it "C".
If it is "d", I like to change it "D".

: :


How can I replace the first letter of $myVar to the big letter?