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  15. <title>Strings (Using as)</title>
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  56. <a name="Strings"></a>
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  58. <p>
  59. Next: <a href="Chars.html#Chars" accesskey="n" rel="next">Chars</a>, Up: <a href="Characters.html#Characters" accesskey="u" rel="up">Characters</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
  60. </div>
  61. <hr>
  62. <a name="Strings-1"></a>
  63. <h4 class="subsubsection">3.6.1.1 Strings</h4>
  64. <a name="index-string-constants"></a>
  65. <a name="index-constants_002c-string"></a>
  66. <p>A <em>string</em> is written between double-quotes. It may contain
  67. double-quotes or null characters. The way to get special characters
  68. into a string is to <em>escape</em> these characters: precede them with
  69. a backslash &lsquo;<samp>\</samp>&rsquo; character. For example &lsquo;<samp>\\</samp>&rsquo; represents
  70. one backslash: the first <code>\</code> is an escape which tells
  71. <code>as</code> to interpret the second character literally as a backslash
  72. (which prevents <code>as</code> from recognizing the second <code>\</code> as an
  73. escape character). The complete list of escapes follows.
  74. </p>
  75. <a name="index-escape-codes_002c-character"></a>
  76. <a name="index-character-escape-codes"></a>
  77. <dl compact="compact">
  78. <dd><a name="index--_005cb-_0028backspace-character_0029"></a>
  79. <a name="index-backspace-_0028_005cb_0029"></a>
  80. </dd>
  81. <dt><kbd>\b</kbd></dt>
  82. <dd><p>Mnemonic for backspace; for ASCII this is octal code 010.
  83. </p>
  84. <a name="index--_005cf-_0028formfeed-character_0029"></a>
  85. <a name="index-formfeed-_0028_005cf_0029"></a>
  86. </dd>
  87. <dt><kbd>backslash-f</kbd></dt>
  88. <dd><p>Mnemonic for FormFeed; for ASCII this is octal code 014.
  89. </p>
  90. <a name="index--_005cn-_0028newline-character_0029"></a>
  91. <a name="index-newline-_0028_005cn_0029"></a>
  92. </dd>
  93. <dt><kbd>\n</kbd></dt>
  94. <dd><p>Mnemonic for newline; for ASCII this is octal code 012.
  95. </p>
  96. <a name="index--_005cr-_0028carriage-return-character_0029"></a>
  97. <a name="index-carriage-return-_0028backslash_002dr_0029"></a>
  98. </dd>
  99. <dt><kbd>\r</kbd></dt>
  100. <dd><p>Mnemonic for carriage-Return; for ASCII this is octal code 015.
  101. </p>
  102. <a name="index--_005ct-_0028tab_0029"></a>
  103. <a name="index-tab-_0028_005ct_0029"></a>
  104. </dd>
  105. <dt><kbd>\t</kbd></dt>
  106. <dd><p>Mnemonic for horizontal Tab; for ASCII this is octal code 011.
  107. </p>
  108. <a name="index--_005cddd-_0028octal-character-code_0029"></a>
  109. <a name="index-octal-character-code-_0028_005cddd_0029"></a>
  110. </dd>
  111. <dt><kbd>\ <var>digit</var> <var>digit</var> <var>digit</var></kbd></dt>
  112. <dd><p>An octal character code. The numeric code is 3 octal digits.
  113. For compatibility with other Unix systems, 8 and 9 are accepted as digits:
  114. for example, <code>\008</code> has the value 010, and <code>\009</code> the value 011.
  115. </p>
  116. <a name="index--_005cxd_002e_002e_002e-_0028hex-character-code_0029"></a>
  117. <a name="index-hex-character-code-_0028_005cxd_002e_002e_002e_0029"></a>
  118. </dd>
  119. <dt><kbd>\<code>x</code> <var>hex-digits...</var></kbd></dt>
  120. <dd><p>A hex character code. All trailing hex digits are combined. Either upper or
  121. lower case <code>x</code> works.
  122. </p>
  123. <a name="index--_005c_005c-_0028_005c-character_0029"></a>
  124. <a name="index-backslash-_0028_005c_005c_0029"></a>
  125. </dd>
  126. <dt><kbd>\\</kbd></dt>
  127. <dd><p>Represents one &lsquo;<samp>\</samp>&rsquo; character.
  128. </p>
  129. <a name="index--_005c_0022-_0028doublequote-character_0029"></a>
  130. <a name="index-doublequote-_0028_005c_0022_0029"></a>
  131. </dd>
  132. <dt><kbd>\&quot;</kbd></dt>
  133. <dd><p>Represents one &lsquo;<samp>&quot;</samp>&rsquo; character. Needed in strings to represent
  134. this character, because an unescaped &lsquo;<samp>&quot;</samp>&rsquo; would end the string.
  135. </p>
  136. </dd>
  137. <dt><kbd>\ <var>anything-else</var></kbd></dt>
  138. <dd><p>Any other character when escaped by <kbd>\</kbd> gives a warning, but
  139. assembles as if the &lsquo;<samp>\</samp>&rsquo; was not present. The idea is that if
  140. you used an escape sequence you clearly didn&rsquo;t want the literal
  141. interpretation of the following character. However <code>as</code> has no
  142. other interpretation, so <code>as</code> knows it is giving you the wrong
  143. code and warns you of the fact.
  144. </p></dd>
  145. </dl>
  146. <p>Which characters are escapable, and what those escapes represent,
  147. varies widely among assemblers. The current set is what we think
  148. the BSD 4.2 assembler recognizes, and is a subset of what most C
  149. compilers recognize. If you are in doubt, do not use an escape
  150. sequence.
  151. </p>
  152. <hr>
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  154. <p>
  155. Next: <a href="Chars.html#Chars" accesskey="n" rel="next">Chars</a>, Up: <a href="Characters.html#Characters" accesskey="u" rel="up">Characters</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="AS-Index.html#AS-Index" title="Index" rel="index">Index</a>]</p>
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