[Gammix]

You could add custom tags to variables while declaring, that's one way.

Here is what i mean:

PHP Code:

new Integer:myInt;
new String:myString[256];
new Float:myFloat; // float already has it's tag
stock function({Integer, Float, String}:param, tag = tagof param) {
    if (tag == tagof(Integer:)) {
        // its an integer
    }
    else if (tag == tagof(String:)) {
        // its a string
    }
    else if (tag == tagof(Float:)) {
        // its a float
    }
} 


There's another way of reading the variable as a string and then do a character check to determine its type.