从混合数组中获取所有可能的结果

I've looked everywhere for this online, but couldn't completely find it. (my PHP and math skills are letting my down for this one...) I have an array containing for example three strings (could also be more!) (for example: "a", "b", "c"). Now I want to make a function which returns ALL possibilities. I looked everywhere and found some nice functions who shifted the array in all possibles ways, but they didn't remove a value one by one. So they had:I've looked everywhere for this online, but cou