user53926:  if ((leftsensor >= 700) && (rightsensor >= 700))
   forward();
       else if((leftsensor <= 150) && (rightsensor <= 150))
   backward();
   else if((leftsensor <= 150) && (rightsensor >= 700))
   turnright();
   else if((leftsensor >= 700) && (rightsensor <= 150))
   turnleft();


user34529: I have somewhat large experience in understanding people that use "bad" english as their secondary language. That's why I assume that even though the question you asked was "What is mean of 700,150 number?" the question you wanted to ask is "What is meaning of numbers 700,150 in code below?"
This was already answered by @MaximilianGerhardt in the comments.
If we assume that leftsensoris an integer value coming from analogRead then it's possible values are between 0 and 1023. The programmed created two arbitrary thresholds of values 700 and 150. Those values were probably calculated experimentally to negate signal noise, sensor imperfections and interference.

53926: <pre><code> if ((leftsensor &gt;= 700) &amp;&amp; (rightsensor &gt;= 700))
   forward();
       else if((leftsensor &lt;= 150) &amp;&amp; (rightsensor &lt;= 150))
   backward();
   else if((leftsensor &lt;= 150) &amp;&amp; (rightsensor &gt;= 700))
   turnright();
   else if((leftsensor &gt;= 700) &amp;&amp; (rightsensor &lt;= 150))
   turnleft();
</code></pre>
 34529: <p>I have somewhat large experience in understanding people that use "bad" english as their secondary language. That's why I assume that even though the question you asked was "<strong>What is mean of 700,150 number?</strong>" the question you wanted to ask is "<strong>What is meaning of numbers 700,150 in code below?</strong>"</p>

<p>This was already answered by @MaximilianGerhardt in the comments.</p>

<p>If we assume that <code>leftsensor</code>is an integer value coming from <code>analogRead</code> then it's possible values are between 0 and 1023. The programmed created two arbitrary thresholds of values 700 and 150. Those values were probably calculated experimentally to negate signal noise, sensor imperfections and interference.</p>
