Compile code error: 'Serial' does not name a type

Question

int LDR_deger = 0;

int Ledpin1 = 12;
int Ledpin2 = 11;
int Ledpin3 = 10;
int Ledpin4 = 9;
int Ledpin5 = 8;

int LDR_pin = 0;

void setup()
{

  Serial.begin(9600);
  pinMode(Ledpin1, OUTPUT);
  pinMode(Ledpin2, OUTPUT);
  pinMode(Ledpin3, OUTPUT);
  pinMode(Ledpin4, OUTPUT);
  pinMode(Ledpin5, OUTPUT);
}
void loop()

{
  LDR_deger = analogRead(LDR_pin);
digitalWrite(Ledpin1,HIGH);
digitalWrite(Ledpin2,HIGH);
digitalWrite(Ledpin3,HIGH);
digitalWrite(Ledpin4,HIGH);
digitalWrite(Ledpin5,HIGH);

if (LDR_deger <= 80 && LDR_deger> 30) {
  digitalWrite(Ledpin1, LOW);
} else{
  digitalWrite(Ledpin1, HIGH);
  if (LDR_deger<= 150 && LDR_deger > 80){
  digitalWrite(Ledpin2, LOW);
  digitalWrite(Ledpin1, LOW);
  }else{
    digitalWrite(Ledpin1, HIGH);
    digitalWrite(Ledpin2, HIGH);
    if (LDR_deger  <= 200 && LDR_deger> 150){
      digitalWrite(Ledpin2, LOW);
      digitalWrite(Ledpin1, LOW);
      digitalWrite(Ledpin3, LOW);
     }else{
      digitalWrite(Ledpin1, HIGH);
      digitalWrite(Ledpin2, HIGH);
      digitalWrite(Ledpin3, HIGH);
      if (LDR_deger <= 1000 && LDR_deger> 300){
      digitalWrite(Ledpin2, LOW);
      digitalWrite(Ledpin1, LOW);
      digitalWrite(Ledpin3, LOW);
      digitalWrite(Ledpin4, LOW);
      digitalWrite(Ledpin5, LOW);
     }else{
      digitalWrite(Ledpin1, HIGH);
      digitalWrite(Ledpin2, HIGH);
      digitalWrite(Ledpin3, HIGH);
      digitalWrite(Ledpin4, HIGH);
      digitalWrite(Ledpin5, HIGH);
     }
       }
     }
   } 
  }
Serial.print("LDR Deger: ");
Serial.print(LDR_deger);
Serial.println(" ");
delay(500);
}

Answer 1

One reason you are receiving the compile error, is due to the code outside of a function. When you write nice, neat, properly formatted code, these errors are easy to spot. The Arduino IDE has a built in feature that will "highlight" a matching curly bracket (or curly brace?).

Answer 2

VE7JRO already has answered your question. Below is not an answer to the question but a better way to program something like you have.

In your case, you need to set 5 pins according. I assume the following lines are just for initialization (and not needed when you set them afterwards to FALSE), as I do not see any delay.

digitalWrite(Ledpin1,HIGH);
digitalWrite(Ledpin2,HIGH);
digitalWrite(Ledpin3,HIGH);
digitalWrite(Ledpin4,HIGH);
digitalWrite(Ledpin5,HIGH);

It is much easier for each pin to set the conditions direction; this will reduce all the if statements and make it very clear for each pin what the value should be.

First we make some variables to prevent duplication. Actually I normally like using bool but it is not a predefined type. Also I like to have the low range on the left and the high range on the right, and using parenthesis. I added the range 200-300, and lower/upper range:

int LDR_deger_min_inf_30 =  (LDR_deger <= 30);
int LDR_deger_30_80      = ((LDR_deger >  30) && (LDR_deger <=   80)); 
int LDR_deger_80_150     = ((LDR_deger >  80) && (LDR_deger <=  150));
int LDR_deger_150_200    = ((LDR_deger > 150) && (LDR_deger <=  200));
int LDR_deger_200_300    = ((LDR_deger > 200) && (LDR_deger <=  300));
int LDR_deger_300_1000   = ((LDR_deger > 300) && (LDR_deger <= 1000));
int LDR_deger_1000_inf   =  (LDR_deger > 1000);

Now you can create a table for each pin (which makes great documentation and a clear overview); I would add it in a comment (if you have no other documentation way):

// pin min_inf_30 30_80 80_150 150_200 200_300 300_1000 1000_inf
//  1     HIGH     LOW    LOW     LOW   HIGH      LOW     HIGH 
//  2     .. (fill in yourself)
//  3     .. (fill in yourself)
//  4     .. (fill in yourself)
//  5     .. (fill in yourself)

Now you can write the pins one by one (I only did the first as example):

digitalWrite(Ledpin1, LDR_deger_min_inf || LDR_deger_200_300 || LDR_deger_1000_inf ? HIGH : LOW);
digitalWrite(Ledpin2, …);