'****' was not declared in this scope

Hallo,
I have a problem with this code.
There is an error: ‘temp’ was not declared in this scope
Can somebody help me?

#define BLYNK_PRINT Serial // Comment this out to disable prints and save space
#include <SPI.h>
#include <ESP8266WiFi.h>
#include <BlynkSimpleEsp8266.h>
#include <SimpleTimer.h>
#include <DHT.h>
int Thermostat = D1;
// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth = “xxxxxxxx”;

// Your WiFi credentials.
// Set password to “” for open networks.
char ssid = “xxxx”;
char pass = “xxxxxxx”;

#define DHTPIN 2 // What digital pin we’re connected to

// Uncomment whatever type you’re using!
#define DHTTYPE DHT22 // DHT 11
//#define DHTTYPE DHT22 // DHT 22, AM2302, AM2321
//#define DHTTYPE DHT21 // DHT 21, AM2301

DHT dht(DHTPIN, DHTTYPE);
SimpleTimer timer;
// This function sends Arduino’s up time every second to Virtual Pin (5).
// In the app, Widget’s reading frequency should be set to PUSH. This means
// that you define how often to send data to Blynk App.
void sendSensor()
{
float h = dht.readHumidity();
float t = dht.readTemperature(); // or dht.readTemperature(true) for Fahrenheit

if (isnan(h) || isnan(t)) {
Serial.println(“Failed to read from DHT sensor!”);
return;
}
// You can send any value at any time.
// Please don’t send more that 10 values per second.
Blynk.virtualWrite(V5, h);
Blynk.virtualWrite(V6, t);
}

BLYNK_WRITE(V6) // V6 is the number of Virtual Pin
{
int temp = param.asInt();
}
BLYNK_WRITE(V4) // V4 is the number of Virtual Pin
{
int slider = param.asInt();
}

void ausschalten()
{
if (temp > slider){digitalWrite(Thermostat, LOW);}
}
void einschalten()
{
if (slider > temp){digitalWrite(Thermostat, HIGH);}
}
void setup()
{
Serial.begin(9600); // See the connection status in Serial Monitor
Blynk.begin(auth, ssid, pass);
pinMode(Thermostat, OUTPUT);
dht.begin();

// Setup a function to be called every second
timer.setInterval(1000L, sendSensor);
timer.setInterval(15000L, ausschalten);
timer.setInterval(15000L, einschalten);
}

void loop()
{
Blynk.run(); // Initiates Blynk
timer.run(); // Initiates SimpleTimer
}

BLYNK_WRITE(V6) // V6 is the number of Virtual Pin
{
  int temp = param.asInt();
}

the temp variable is declared in this function so is only available in that function.

However, the program tries to use it in other functions, hence the error message

You have the same problem with the slider variable

BLYNK_WRITE(V4) // V4 is the number of Virtual Pin
{
  int slider = param.asInt();
}

Declare these variables as global at the top of the program and delete the type specifier when you use them in these 2 functions

This article on scope may be of interest.