105 lines
3.4 KiB
HTML
105 lines
3.4 KiB
HTML
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<html>
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<head>
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<title>realloc</title>
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<link rel="stylesheet" type="text/css" media="all" href="../man.css">
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</head>
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<body bgcolor=#ffffff>
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<h2 align=center>realloc</h2>
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<h4 align=center>OS/161 Reference Manual</h4>
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<h3>Name</h3>
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<p>
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realloc - resize allocated memory
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</p>
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<h3>Library</h3>
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<p>
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Standard C Library (libc, -lc)
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</p>
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<h3>Synopsis</h3>
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<p>
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<tt>#include <stdlib.h></tt><br>
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<br>
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<tt>void *</tt><br>
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<tt>realloc(void *</tt><em>ptr</em><tt>,
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size_t </tt><em>newsize</em><tt>);</tt>
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</p>
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<h3>Description</h3>
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<p>
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<tt>realloc</tt> attempts to change the size of the memory block
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pointed to by <em>ptr</em> to <em>newsize</em>, causing the block to
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shrink or grow as necessary. If the size cannot be changed, a new
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block is allocated and the contents (up to the lesser of the previous
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size and <em>newsize</em>) are copied, then the old block is freed.
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</p>
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<p>
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The size of <tt>NULL</tt> is treated as 0. If the size is increased,
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any newly allocated space has undefined contents. If the size is
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decreased, the space discarded may no longer be accessed. Otherwise
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the contents of the memory block are preserved.
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</p>
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<p>
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<em>ptr</em> must be NULL or have been previously returned by
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<A HREF=malloc.html>malloc</A>, <A HREF=calloc.html>calloc</A>, or
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realloc.
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</p>
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The alignment and other restrictions described for
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<A HREF=malloc.html>malloc</A> apply equally to realloc.
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<p>
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<h3>Return Values</h3>
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<p>
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<tt>realloc</tt> returns a pointer to the resized memory block. This
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may not be the same pointer as <em>ptr</em>. If so, the old block is
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invalidated and <em>ptr</em> becomes invalid.
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</p>
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<p>
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If the operation cannot be performed at all, NULL is returned and
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the original block pointed to by <em>ptr</em> is untouched
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and remains valid.
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</p>
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<h3>See Also</h3>
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<p>
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<A HREF=calloc.html>calloc</A>,
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<A HREF=malloc.html>malloc</A>,
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<A HREF=free.html>free</A>
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</p>
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</body>
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</html>
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