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copied!<p>The line</p> <pre><code>int j = liczba.charAt(i) - 47; </code></pre> <p>Subtracts the character code of (i+1)th character <code>liczba</code> by 47. Refering to an <a href="http://www.asciitable.com/" rel="nofollow">ASCII table</a>, 47 maps to "/", whose ASCII code is one less than "0". </p> <p>Note that I am assuming the following, as your code appears to be in Java.</p> <ul> <li>String indexes starts at zero i.e. first character has index 0, second character has index 1, and so on </li> <li>It seems that characters and integers can be used interchangeably, because a character is internally represented by an integer, namely, the ASCII code of the character.</li> <li>That said, the <code>char</code> type is actually an integer type, with less range</li> </ul> <p>Hence, this code is to turn characters "0" to the integer 1, "1" to the integer 2, etc. </p> <p>For example, when the 1st character (<code>liczba.charAt(0)</code>) is the character <code>0</code>, <code>liczba.charAt(0)</code> returns character <code>'0'</code>, which is also equals to number <code>48</code> -- because <code>'0'</code> has an ASCII code of 48. </p> <p>Subtracts 48 with 47 gets 1, so it would convert character '<code>0</code>' to integer 1. </p> <p><strong>However</strong> it seems that this code could cause array index out of bounds error (assuming zero-based array indexes). when a digit is <code>'9'</code>, this line returns 10. This would cause an aforementioned error. Unless this code's language's array are 1-based. However, even in this case, this line</p> <pre><code>int count = digits[0]; </code></pre> <p>would simply fail. This code seems to fail with the common <a href="http://en.wikipedia.org/wiki/Off_by_one_error" rel="nofollow">Off by one error</a></p> <p>I believe this line should actually read </p> <pre><code>int j = liczba.charAt(i) - 48; </code></pre> <p>so that character <code>'0'</code> is converted to number 0.</p> <p>If this still disturb you, you may change this line to</p> <pre><code>int j = liczba.charAt(i) - '0'; </code></pre> <p>so it would be clearer. Subtract the code of <code>'1'</code> and the code of <code>'0'</code> gets you the integer 1, clear enough :) </p>

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