String to Int

I've set up a message system which receives serial data and takes different actions based on the first number in the data.

so "1 hello" prints hello to my LCD - this all works fine.

I want "3 543" to assign 543 to an int. I have managed to chop of the 3 of the string and store the new string as "543" but i'm stuck with how to convert the "543" to an int with the value "543"

This is what i have to chop down the string:

#include <stdio.h>
#include <string.h>
     char str1[] = "3 543";
     char str2[15];
     int  i;
    int LEDval =0;
   
 
  void setup()
  {

Serial.begin(19200);   

    for (i=0; str1[i]; i++)
       str2[i] = str1[i+2];
    str2[i] = '\0';
    Serial.println(str2);
  
 }
 
 void loop(){
 }

How do i get my int? I'm really confused.

Thanks,

John.

Ah ok, thanks.