Help with password code

hey guys, little new arduino , wondering if on 1 of projects working on right now.

so happens have string called "key" has password stored on beforehand such "banana" when type serial monitor send typed lcd , if typed , password same there message on lcd saying "correct password". if not correct password there try again message. having trouble getting serial.read() compared "key" variable in if statements. grateful if out, code below.

code: [select]

const int rs = 12, en = 11, d4 = 5, d5 = 4, d6 = 3, d7 = 2;
#include <liquidcrystal.h>
liquidcrystal lcd(rs, en, d4, d5, d6, d7);
string key = "radical dude";

void setup() {
  // set lcd's number of columns , rows:
  lcd.begin(16, 2);
  // initialize serial communications:
  serial.begin(9600);
 
}

void loop() {
  // when characters arrive on serial port...
  if (serial.available()) {
    // wait bit entire message arrive
    delay(100);
    // clear screen
    lcd.clear();
    // read available characters
    while (serial.available() > 0) {
      // display each character lcd
      lcd.write(serial.read());
    }
  }
  if (serial.read == key){
    lcd.clear();
    lcd.print("password accepted");
  }
  if (serial.read != key){
    lcd.clear();
    lcd.print("incorrect");
  }
 
}

in if statements keeps saying have "non-static member function".

second guessing happens in asynchronous line synchronous code calling trouble...

code: [select]

  if (serial.available()) {
    // wait bit entire message arrive
    delay(100);

read serial input basics , familiar c functions in stdlib.h , string.h , drop usage of string class

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