You do not define functions inside other functions -.-
You don't use setstring or addstring in GS2.
PHP Code:
//GS1
setstring this.string,This is a String;
setstring this.array,This,is,a,String,Array;
addstring this.array,I am adding this;
//GS2
this.string = "This is a String";
this.array = {"This", "is", "a", "String", "Array"};
this.array.add("I'm adding this");