Error - invalid conversion from 'char' to 'const char*', Not able to connect on pubnub server using node mcu [duplicate]

Question

I have node mcu with ESP8266 wifi module. When i am trying to upload an example code then its not working.

This is the Error:-

inline PubSubClient* PubNub::subscribe(const char* channel, int timeout)

                      ^

exit status 1
invalid conversion from 'char' to 'const char*' [-fpermissive]

Code:-

#include <ESP8266WiFi.h>
#define PubNub_BASE_CLIENT WiFiClient
#define PUBNUB_DEFINE_STRSPN_AND_STRNCASECMP


#include <PubNub.h>

const char *ssid =  "mym404";     // replace with your wifi ssid and wpa2 key
const char *pass =  "786110786";

char pubkey = 'pub-c-4a9cdbca-5688-4939-a852-f63cf6743980';
char subkey = 'sub-c-9b4067ae-1293-11e9-b4a6-026d6924b094';

char pubchannel = 'demo_keyset';
char subchannel = 'demo_keyset';

void setup() {
    /* For debugging, set to speed of your choice */
    Serial.begin(9600);

       Serial.println("Connecting to ");
       Serial.println(ssid); 

       WiFi.begin(ssid, pass); 
       while (WiFi.status() != WL_CONNECTED) 
          {
            delay(500);
            Serial.print(".");
          }
      Serial.println("");
      Serial.println("WiFi connected");

    /* Start the Pubnub library by giving it a publish and subscribe
       keys */
    PubNub.begin(pubkey, subkey);
}

void loop() {
    /* Maintain DHCP lease. For other HW, you may need to do
       something else here, or maybe nothing at all. */


    /* Publish message. You could use `auto` here... */
    PubNonSubClient *pclient = PubNub.publish(pubchannel, "\"message\"");
    if (!pclient) return;
    PublishCracker cheez;
    cheez.read_and_parse(pclient);
    /** You're mostly interested in `outcome()`, and,
        if it's "failed", then `description()`. 
    */
    Serial.print("Outcome: "); Serial.print(cheez.outcome());
    Serial.print(' '); Serial.println(cheez.to_str(cheez.outcome()));
    Serial.print("description: "); Serial.println(cheez.description());
    Serial.print("timestamp: "); Serial.println(cheez.timestamp());
    Serial.print("state: "); Serial.print(cheez.state());
    Serial.print(' '); Serial.println(cheez.to_str(cheez.state()));
    pclient->stop();

    /* Wait for news. */
    PubSubClient *sclient = PubNub.subscribe(subchannel);
    if (!sclient) return; // error
    String msg;
    SubscribeCracker ritz(sclient);
    while (!ritz.finished()) {
        ritz.get(msg);
        if (msg.length() > 0) {
            Serial.print("Received: "); Serial.println(msg);
        }
    }
    sclient->stop();

    delay(1000);
}

Code is taken from pubnub arduino github example - https://github.com/pubnub/arduino/blob/master/examples/AdafruitFeatherM0WINC1500/AdafruitFeatherM0WINC1500.ino

Answer 1

problem was in the declaration of API keys and channel on the above code

Here is the right code:-

const char * pubkey = "publisher key from your account";
const char * subkey = "subscriber key from your account";

const char * pubchannel = "demo_keyset";
const char * subchannel = "demo_keyset";