index of non-alphanumeric character in string

        public static int IndexOfNonAlphanumericCharacter(string p, bool excludeSpaces){
            int index = -1;

            if(p.Length < 1){
                //done
            }else{
                char[] chars = p.ToCharArray();
                for(int i=0; i < chars.Length; i++){
                    if(IsNonAlphaNumChar(chars[i])){
                        if(chars[i] == ' '){
                            if(excludeSpaces){
                                //ignore
                            }else{
                                index = i;
                                break;
                            }
                        }else{
                            index = i;
                        }

                    }
                }
            }

            return index;
        }