int _rename_r(void *reent, const char *old, const char *new);
```### Description
Use rename to establish a new name (the string at new) for a file now known by the string at old. After a successful rename, the file is no longer accessible by the string at old.
If rename fails, the file named *old is unaffected. The conditions for failure depend on the host operating system.
The alternate function _rename_r is a reentrant version. The extra argument reent is a pointer to a reentrancy structure.### Returns
The result is either 0 (when successful) or -1 (when the file could not be renamed).
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**Authoritative source**: BUSMASTER DITA help source `rename.dita`, compiled into `BUSMASTER.CHM` with the application.
