Guardian Native C Library Calls Reference Manual (G06.28+, H06.05+)

Guardian Native C Library Calls (t - z) ungetc(3)

NAME

ungetc - Pushes a character back into the input stream

LIBRARY

G-series native Guardian processes: $SYSTEM.SYSnn.ZCRTLSRL

G-series native OSS processes: /G/system/sysnn/zcrtlsrl

H-series native Guardian processes: $SYSTEM.ZDLLnnn.ZCRTLDLL

H-series OSS processes: /G/system/zdllnnn/zcrtldll

SYNOPSIS

#include <stdio.h>

int ungetc(

int c,

FILE *stream);

PARAMETERS

c Speciﬁes a byte to be inserted into the input stream.

stream Speciﬁes the input stream.

DESCRIPTION

The ungetc() function converts the byte speciﬁed by the c parameter into an unsigned char and

inserts it into the buffer associated with the input stream speciﬁed by the stream parameter. This

causes the next call to the getc() function to return c.

If the c parameter has a value equal to EOF, the ungetc() function does not place anything in the

buffer and the input stream is unchanged.

You can always push one byte back onto a stream. The fseek() subroutine erases all memory of

inserted characters.

NOTES

The ungetc() function does not have any effect on the external storage corresponding to the

stream.

RETURN VALUES

The ungetc() returns c if it succeeds in inserting the byte in the stream. Otherwise, it returns a

value of EOF.

ERRORS

None. This function does not set errno.

RELATED INFORMATION

Functions: fseek(3), getc(3), getwc(3), setbuf(3), ungetwc(3).

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