5.2 Using Standard I/O for Database Files

If ‘-’ is supplied as a record name to any of the functions that read or write header files, the ‘hea’ file is taken to be the standard input or output, as appropriate. If the name of a signal file is specified in the ‘hea’ file (or in the array of WFDB_Siginfo objects passed to osigfopen) as ‘-’, the standard input (output) is used by getvec (putvec). If the name of an annotator is given in the array of WFDB_Anninfo objects as ‘-’, the standard input (output) is used by getann (putann). If the name of a calibration file is given as ‘-’, the standard input (output) is used by calopen (newcal).

Under MS-DOS, these features may not always be usable, since the standard input and output are usually opened in “text” mode (which is unsuitable for binary database files).

Although the WFDB library does not forbid the use of the standard input or output for more than one function (e.g., as both a signal file and an annotation file), such use is in general a gross error that is likely to lead to unintended results.