user51274: I tried to represent the values of TSL 2591 Adafruit light sensor on my Arduino Serial Monitor, but for some reason, I could not do that. The Arduino Serial Monitor just enters some blank values and scrolls down. 
Here is the code:
uint16_t x = tsl.getLuminosity(TSL2591_VISIBLE);
y = float(tsl.getLuminosity(TSL2591_VISIBLE));
z = (y, DEC);
Serial.write((byte)z);

x, y, and z are floats initially.

user37622: Use Serial.println(x); to print a number as text. Function write() sends the raw byte and Serial Monitor shows the character with that ASCII code, which is not valid or a not visible control character.

For the z = (y, DEC); from Wikipedia:

In the C and C++ programming languages, the comma operator (represented by the token ,) is a binary operator that evaluates its first operand and discards the result, and then evaluates the second operand and returns this value (and type). 

so z is always 10 (value of constant DEC), which is ASCII code for the new line character

51274: <p>I tried to represent the values of TSL 2591 Adafruit light sensor on my Arduino Serial Monitor, but for some reason, I could not do that. The Arduino Serial Monitor just enters some blank values and scrolls down. 
Here is the code:</p>

<pre class="lang-c++ prettyprint-override"><code>uint16_t x = tsl.getLuminosity(TSL2591_VISIBLE);
y = float(tsl.getLuminosity(TSL2591_VISIBLE));
z = (y, DEC);
Serial.write((byte)z);
</code></pre>

<p><code>x</code>, <code>y</code>, and <code>z</code> are floats initially.</p>
 37622: <p>Use Serial.println(x); to print a number as text. Function write() sends the raw byte and Serial Monitor shows the character with that ASCII code, which is not valid or a not visible control character.</p>

<hr>

<p>For the <code>z = (y, DEC);</code> from Wikipedia:</p>

<blockquote>
  <p>In the C and C++ programming languages, the comma operator (represented by the token ,) is a binary operator that evaluates its first operand and discards the result, and then evaluates the second operand and returns this value (and type). </p>
</blockquote>

<p>so <code>z</code> is always 10 (value of constant DEC), which is ASCII code for the new line character</p>
