Temperature display using LCD

#include <rgb_lcd.h>

#include<Wire.h>


rgb_lcd lcd;

const int colorR=0;
const int colorG=255;
const int colorB=0;
int a;
float temp;
int B=3975;
float resistance;
int button=3;

void setup() {
  // put your setup code here, to run once:
pinMode(button,INPUT);
Serial.begin(9600);
lcd.begin(16,2);

lcd.setRGB(colorR,colorG,colorB);

lcd.print("hello world!");

delay(1000);
}

void loop() {
  // put your main code here, to run repeatedly:
a=analogRead(0);
resistance=(float)(1023-a)*10000/a;
temp=1/(log(resistance/10000)/B+1/298.15)-273.15;
temp=temp+32;
lcd.setCursor(0,1);
int buttonState=digitalRead(button);
if(buttonState==1)
{
lcd.print(temp);
lcd.print("*C");
}
else
{
 lcd.clear();
  }
delay(100);
}