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  53. <a name="gcvt_002c-gcvtf_002d_002d_002dformat-double-or-float-as-string"></a>
  54. <h3 class="section">2.14 <code>gcvt</code>, <code>gcvtf</code>&mdash;format double or float as string</h3>
  55. <a name="index-gcvt"></a>
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  57. <p><strong>Synopsis</strong>
  58. </p><div class="example">
  59. <pre class="example">#include &lt;stdlib.h&gt;
  60. char *gcvt(double <var>val</var>, int <var>precision</var>, char *<var>buf</var>);
  61. char *gcvtf(float <var>val</var>, int <var>precision</var>, char *<var>buf</var>);
  62. </pre></div>
  63. <p><strong>Description</strong><br>
  64. <code>gcvt</code> writes a fully formatted number as a null-terminated
  65. string in the buffer <code>*<var>buf</var></code>. <code>gcvtf</code> produces corresponding
  66. character representations of <code>float</code> numbers.
  67. </p>
  68. <p><code>gcvt</code> uses the same rules as the <code>printf</code> format
  69. &lsquo;<code>%.<var>precision</var>g</code>&rsquo;&mdash;only negative values are signed (with
  70. &lsquo;<code>-</code>&rsquo;), and either exponential or ordinary decimal-fraction format
  71. is chosen depending on the number of significant digits (specified by
  72. <var>precision</var>).
  73. </p>
  74. <br>
  75. <p><strong>Returns</strong><br>
  76. The result is a pointer to the formatted representation of <var>val</var>
  77. (the same as the argument <var>buf</var>).
  78. </p>
  79. <br>
  80. <p><strong>Portability</strong><br>
  81. Neither function is ANSI C.
  82. </p>
  83. <p>Supporting OS subroutines required: <code>close</code>, <code>fstat</code>, <code>isatty</code>,
  84. <code>lseek</code>, <code>read</code>, <code>sbrk</code>, <code>write</code>.
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