Author Topic: 50$ Robot: expected identifier or '(' before 'while'  (Read 1365 times)

0 Members and 1 Guest are viewing this topic.

Offline nfwillTopic starter

  • Beginner
  • *
  • Posts: 2
  • Helpful? 0
50$ Robot: expected identifier or '(' before 'while'
« on: May 26, 2011, 08:34:12 PM »
Hello,
I have been following the 50$ robot tutorial and I have only the programming step left!

I added the Photovore_v1.c to source files under the AVR Studio, and followed the tutorial to the point of "Rebuild All"

At that point, I received 1 error and 3 warnings; the error being "expected identifier or '(' before while."

Here is the code that I copied and pasted in:



LED_off();//turn LED on


   while(1)
      {
      //store sensor data
      sensor_left=a2dConvert8bit(5);
      sensor_right=a2dConvert8bit(4);


      //detects more light on left side of robot
      if(sensor_left > sensor_right && (sensor_left - sensor_right) > threshold)
         {//go left
         servo_left(44);
         servo_right(44);
         }

      //detects more light on right side of robot
      else if(sensor_right > sensor_left && (sensor_right - sensor_left) > threshold)
         {//go right
         servo_left(25);
         servo_right(25);
         }

      //light is about equal on both sides
      else
         {//go straight
         servo_left(25);
         servo_right(44);
         }


      /* Servo Test Code
      i=250;
      while(i>0)
         {
         servo_left(40);
         i--;
         }

      i=250;
      while(i>0)
         {
         servo_left(24);
         i--;
         }
      */

      //rprintf("Initialization Complete\r\n");
      
      //output message to serial (use hyperterminal)
      //print("Hello, World! Read My Analog: %u\r\n", sensor_0);

      delay_cycles(500);//a small delay to prevent crazy oscillations
      }





My Intuition of my issue:
I have little knowledge of C; I am somewhat conversant in Python and Basic, I would think there must be "definitions" or parameters that I am missing. The code above is simply the bit that the downloaded Photovore_v1.c file shows to be added.
Any help is appreciated!

nfwill

Offline Admin

  • Administrator
  • Supreme Robot
  • *****
  • Posts: 11,663
  • Helpful? 169
    • Society of Robots
Re: 50$ Robot: expected identifier or '(' before 'while'
« Reply #1 on: May 26, 2011, 08:42:49 PM »
It looks right . . . I suspect there is other code above or below that, which could cause a problem . . .

Also, try to match the line number of the error to the actual code.

Offline garrettg84

  • Robot Overlord
  • ****
  • Posts: 187
  • Helpful? 8
  • Armchair Roboticist Extraordinaire
Re: 50$ Robot: expected identifier or '(' before 'while'
« Reply #2 on: May 27, 2011, 07:16:57 AM »
is LED_off() supposed to be a function?

the following code would make this a function

Code: [Select]
LED_off() {//turn LED on
   while(1)
      {
      //store sensor data
      sensor_left=a2dConvert8bit(5);
      sensor_right=a2dConvert8bit(4);


      //detects more light on left side of robot
      if(sensor_left > sensor_right && (sensor_left - sensor_right) > threshold)
         {//go left
         servo_left(44);
         servo_right(44);
         }

      //detects more light on right side of robot
      else if(sensor_right > sensor_left && (sensor_right - sensor_left) > threshold)
         {//go right
         servo_left(25);
         servo_right(25);
         }

      //light is about equal on both sides
      else
         {//go straight
         servo_left(25);
         servo_right(44);
         }


      /* Servo Test Code
      i=250;
      while(i>0)
         {
         servo_left(40);
         i--;
         }

      i=250;
      while(i>0)
         {
         servo_left(24);
         i--;
         }
      */

      //rprintf("Initialization Complete\r\n");
     
      //output message to serial (use hyperterminal)
      //print("Hello, World! Read My Analog: %u\r\n", sensor_0);

      delay_cycles(500);//a small delay to prevent crazy oscillations
      }


Based on code spacing and the trailing '}' you have either not copied the entire code, or the code you copied was bunk to begin with.
-garrett

Offline richiereynolds

  • Full Member
  • ***
  • Posts: 112
  • Helpful? 3
Re: 50$ Robot: expected identifier or '(' before 'while'
« Reply #3 on: May 27, 2011, 09:52:09 AM »
Is that the whole file you're posting or a snippet? The whole file should probably have some #includes etc. at the top

Offline nfwillTopic starter

  • Beginner
  • *
  • Posts: 2
  • Helpful? 0
Re: 50$ Robot: expected identifier or '(' before 'while'
« Reply #4 on: May 27, 2011, 09:08:57 PM »
Thank you for your responses Admin, garrettg84 and richiereynolds.

I first tried garrettg84's code; the compiler unfortunately complained and mentioned more 'undefined variables'.

My problem ended up being I read too much into the process, and richiereynolds implication that a 'snippet' can be the source of my issues helped. The code I did use was a snippet; complications I faced with AVR Studio caused me to use the snippet which at the time made a lot of sense: the 'entire code' mentioned using a specific part of its own code, perhaps I misunderstood. Getting the entire code into AVR through crude 'copying and pasting' rather than browsing through the files allowed it to successfully compile and functions correctly. I am very excited to be finishing up my first robot!

Thank you all for your time and help!

Much Appreciated,

nfwill
« Last Edit: May 27, 2011, 09:14:19 PM by nfwill »

 


Get Your Ad Here

data_list