user33278: I have tried using the thingspeak-arduino library and tested some of the examples: 
#include <WiFi.h>
#include <WiFiClient.h>
#include <SPI.h>
#include <ThingSpeak.h>
char ssid[] = "Benok4G";    //  your network SSID (name)
char pass[] = "password";   // your network password
WiFiClient  client;

unsigned long myChannelNumber = 344468;
const char * myReadAPIKey = "xxxxxxxxx";


void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  WiFi.begin(ssid, pass);
  ThingSpeak.begin(client);    
}

void loop() {
  // put your main code here, to run repeatedly:
  float voltage = ThingSpeak.readFloatField(myChannelNumber, 1, myReadAPIKey);

  Serial.print("Latest voltage is: ");
  Serial.print(voltage);
  Serial.println("V");

  delay(30000);
}

When i run this code, I get this on the Serial Monitor.

Why is it 0.00? It's supposed to be 24.0
http://184.106.153.149/channels/344468/fields/1/last
Did I do something wrong? I am very frustrated because I've tried a lot of methods already just to fetch the data from ThingSpeak to my Arduino using ESP8266. I can send but when receiving I am really lost and confused.

user26916: #include <WiFi.h>

From the WiFi library reference page:

With the Arduino WiFi Shield, this library allows an Arduino board to connect to the internet.

From the Arduino WiFi Shield product page:

It is based on the HDG204 Wireless LAN 802.11b/g System in-Package. An AT32UC3 provides a network (IP) stack capable of both TCP and UDP.

But you're not using an Arduino WiFi Shield or anything compatible. You're using an ESP8266 which is completely different. Thus you can't use the WiFi library for your project.
Instead you will need to use the appropriate ESP8266 library. If you are programming the ESP8266 directly that will be the ESP8266WiFi library, which is bundled with the ESP8266 core for Arduino. If you are using the ESP8266 as a WiFi module controlled via AT commands that will be the WiFiEsp library

33278: <p>I have tried using the <a href="https://github.com/mathworks/thingspeak-arduino" rel="nofollow noreferrer">thingspeak-arduino library</a> and tested some of the examples: </p>

<pre class="lang-cpp prettyprint-override"><code>#include &lt;WiFi.h&gt;
#include &lt;WiFiClient.h&gt;
#include &lt;SPI.h&gt;
#include &lt;ThingSpeak.h&gt;
char ssid[] = "Benok4G";    //  your network SSID (name)
char pass[] = "password";   // your network password
WiFiClient  client;

unsigned long myChannelNumber = 344468;
const char * myReadAPIKey = "xxxxxxxxx";


void setup() {
  // put your setup code here, to run once:
  Serial.begin(9600);
  WiFi.begin(ssid, pass);
  ThingSpeak.begin(client);    
}

void loop() {
  // put your main code here, to run repeatedly:
  float voltage = ThingSpeak.readFloatField(myChannelNumber, 1, myReadAPIKey);

  Serial.print("Latest voltage is: ");
  Serial.print(voltage);
  Serial.println("V");

  delay(30000);
}
</code></pre>

<p>When i run this code, I get this on the Serial Monitor.
<a href="https://i.stack.imgur.com/0Yv7X.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0Yv7X.jpg" alt="enter image description here"></a></p>

<p>Why is it 0.00? It's supposed to be 24.0</p>

<p><a href="http://184.106.153.149/channels/344468/fields/1/last" rel="nofollow noreferrer">http://184.106.153.149/channels/344468/fields/1/last</a></p>

<p>Did I do something wrong? I am very frustrated because I've tried a lot of methods already just to fetch the data from ThingSpeak to my Arduino using ESP8266. I can send but when receiving I am really lost and confused.</p>
 26916: <pre><code>#include &lt;WiFi.h&gt;
</code></pre>

<p>From the <a href="https://www.arduino.cc/en/Reference/WiFi" rel="nofollow noreferrer">WiFi library reference page</a>:</p>

<blockquote>
  <p>With the Arduino WiFi Shield, this library allows an Arduino board to connect to the internet.</p>
</blockquote>

<p>From the <a href="https://store.arduino.cc/arduino-wifi-shield" rel="nofollow noreferrer">Arduino WiFi Shield product page</a>:</p>

<blockquote>
  <p>It is based on the HDG204 Wireless LAN 802.11b/g System in-Package. An AT32UC3 provides a network (IP) stack capable of both TCP and UDP.</p>
</blockquote>

<p>But you're not using an Arduino WiFi Shield or anything compatible. You're using an ESP8266 which is completely different. Thus you can't use the WiFi library for your project.</p>

<p>Instead you will need to use the appropriate ESP8266 library. If you are programming the ESP8266 directly that will be the <a href="https://github.com/esp8266/Arduino/blob/master/doc/esp8266wifi/readme.rst" rel="nofollow noreferrer">ESP8266WiFi library</a>, which is bundled with the <a href="https://github.com/esp8266/Arduino" rel="nofollow noreferrer">ESP8266 core for Arduino</a>. If you are using the ESP8266 as a WiFi module controlled via AT commands that will be the <a href="https://github.com/bportaluri/WiFiEsp" rel="nofollow noreferrer">WiFiEsp</a> library</p>
