php sort filenames with an underscore

Question

I have an array of filenames that I aquire using DirectoryIterator. I am trying to get the filenames to sort so they would be in order like so, this is the way they appear o

Answer 1

try using

for(i=0;i a[j]) 
{
temp = a[i];
a[i] = a[j];
a[j] = temp;
}}}}}