Trouble with boolean value returning twice (Arduino) - c++

Question

I'm working with a project that involves a Arduino UNO card and JAVA. The Arduino UNO would be the client and JAVA the server.
The problem is that my verify function is returning 0 twice when it's false, why does it do that and if true it returns 1 and 0 which is weird.
I just want it to return once, and not false false like the example here:
#include <SPI.h>
#include <Ethernet.h>
byte mac[] = { 0x90, 0xA2, 0xDA, 0x0F, 0x50, 0x35 };
IPAddress arduino(192,168,0,12);
IPAddress server(192,168,0,15);
EthernetClient client;
String username[] = {"Admin","Skut","Arbek","Kubda"};
String password[] = {"12344","stra","124ssgra","!#¤%"};
String readString;
void setup() {
Serial.begin(9600);
Ethernet.begin(mac,arduino);
Serial.println("Connecting...");
if (client.connect(server, 8888)){
Serial.println("Connected to Server");
}
else {
Serial.println("Connecting failed");
}
}
boolean verify(String firstText, String secondText){
for(int i = 0; i <= 3 ; i++){
if((username[i] == firstText ) && (password[i] == secondText)){
return true;
}
}
return false;
}
void clientRead() {
while (client.available()) {
//delay(10);
if (client.available() >0) {
char c = client.read();
readString += c;
}
}
}
void loop(){
if (client.available() > 0){
readString = "";
clientRead();
Serial.println(readString);
int n = readString.length();
int commaIndex = readString.indexOf(';');
int lastIndex = readString.lastIndexOf(n);
String firstText = readString.substring(0, commaIndex);
String secondText = readString.substring(commaIndex + 1 , lastIndex);
Serial.println(firstText);
Serial.println(secondText);
Serial.println(verify(firstText, secondText));
}
if (!client.connected()){
Serial.println("Server disconnected!");
client.stop();
client.flush();
while(true);
}
}
I've tried sending ( Admin;12344 ) to the arduino from the server and this is what I get:
Connecting...
Connected to Server
Admin;12344
Admin
12344
1
0

Answer 1

while (client.available())
is not reliable. It might terminate earlier than what you expect depending on the relative speed of the device. Most probably you are getting partial data on the first try and another batch on second one (probably only \n). Instead of relying on available, use a marker to end the data.

Answer 2

The problem lies with what is being sent. If you look at the hex values of your output you will notice 7 CRLF between the 1 and 0. One of those belongs to the println of 1. The next 6 is exactly the output of 3 println. What is being printed 3 times? One CRLF, thats all. Because of the way you do the substrings all three outputs:
Serial.println(readString);
Serial.println(firstText);
Serial.println(secondText);
will print the very same CRLF along with their respective CRLF of the println.
So your answer is that you are sending a CRLF at the end of the line which is sent to the Arduino. Consider Cem Kalyoncu's answer about how to properly handle the reading and also do not send a CRLF to the Arduino at the end of the authentication line and you will most probably be fine.
I also suggest you read up on why not to use String in arduino. It is a world of memory and space problems you bring forth if you keep on using it.

Answer 3

Instead of if((username[i] == firstText ) && (password[i] == secondText)), try to use if(( firstText.equals(username[i]) ) && ( secondText.equals(password[i]) ))
I think the == don't compare the value of strings.