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84 lines
6.9 KiB
HTML
84 lines
6.9 KiB
HTML
14 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<p><strong>Reference</strong> <a class='wikilink' href='index.html'>Language</a> | <a class='wikilink' href='Libraries.html'>Libraries</a> | <a class='wikilink' href='Comparison.html'>Comparison</a> | <a class='wikilink' href='Changes.html'>Changes</a>
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<p class='vspace'></p><p><a class='wikilink' href='StringClass.html'>String</a>
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<p class='vspace'></p><h2>String()</h2>
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<h4>Description</h4>
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<p>Constructs an instance of the String class. There are multiple versions that construct Strings from different data types (i.e. format them as sequences of characters), including:
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</p><ul><li>a constant string of characters, in double quotes (i.e. a char array)
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</li><li>a single constant character, in single quotes
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</li><li>another instance of the String object
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</li><li>a constant integer or long integer
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</li><li>a constant integer or long integer, using a specified base
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</li><li>an integer or long integer variable
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</li><li>an integer or long integer variable, using a specified base
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</li></ul><p class='vspace'></p><p>Constructing a String from a number results in a string that contains the ASCII representation of that number. The default is base ten, so
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</p>
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<p class='vspace'></p><p><code>String thisString = String(13)</code>
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</p>
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<p class='vspace'></p><p>gives you the String "13". You can use other bases, however. For example,
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</p>
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<p class='vspace'></p><p><code>String thisString = String(13, HEX)</code>
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</p>
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<p class='vspace'></p><p>gives you the String "D", which is the hexadecimal representation of the decimal value 13. Or if you prefer binary,
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</p>
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<p class='vspace'></p><p><code>String thisString = String(13, BIN)</code>
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</p>
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<p class='vspace'></p><p>gives you the String "1011", which is the binary representation of 13.
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</p>
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<p class='vspace'></p><h4>Syntax</h4>
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<p>String(val)<br />String(val, base)
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</p>
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<p class='vspace'></p><h4>Parameters</h4>
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<p>val: a variable to format as a String - <em>string</em>, <em>char</em>, <em>byte</em>, <em>int</em>, <em>long</em>, <em>unsigned int</em>, <em>unsigned long</em><br />base (<em>optional</em>) - the base in which to format an integral value
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</p>
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<p class='vspace'></p><h4>Returns</h4>
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<p>an instance of the String class
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</p>
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<p class='vspace'></p><h3>Examples</h3>
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<p>All of the following are valid declarations for Strings.
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</p><pre>
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String stringOne = "Hello String"; // using a constant String
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String stringOne = String('a'); // converting a constant char into a String
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String stringTwo = String("This is a string"); // converting a constant string into a String object
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String stringOne = String(stringTwo + " with more"); // concatenating two strings
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String stringOne = String(13); // using a constant integer
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String stringOne = String(analogRead(0), DEC); // using an int and a base
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String stringOne = String(45, HEX); // using an int and a base (hexadecimal)
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String stringOne = String(255, BIN); // using an int and a base (binary)
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String stringOne = String(millis(), DEC); // using a long and a base
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</pre>
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<p class='vspace'></p><h4>See also</h4>
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<ul><li><a class='createlinktext' rel='nofollow'
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href='#'>= (assignment)</a><a rel='nofollow'
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class='createlink' href='#'>?</a>
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</li><li><a class='createlinktext' rel='nofollow'
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href='#'>~String</a><a rel='nofollow'
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class='createlink' href='#'>?</a>()
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</li></ul><p class='vspace'></p><p><a class='wikilink' href='index.html'>Reference Home</a>
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</p>
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<p class='vspace'></p><p><em>Corrections, suggestions, and new documentation should be posted to the <a class='urllink' href='http://www.arduino.cc/cgi-bin/yabb2/YaBB.pl?board=swbugs' rel='nofollow'>Forum</a>.</em>
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</p>
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<p class='vspace'></p><p>The text of the Arduino reference is licensed under a
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<a class='urllink' href='http://creativecommons.org/licenses/by-sa/3.0/' rel='nofollow'>Creative Commons Attribution-ShareAlike 3.0 License</a>. Code samples in the reference are released into the public domain.
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