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.IX Title "BN_zero 3"
.TH BN_zero 3 "0.9.5a" "2000-07-23" "OpenSSL"
.UC
.SH "NAME"
BN_zero, BN_one, BN_set_word, BN_get_word \- \s-1BIGNUM\s0 assignment operations
.SH "LIBRARY"
libcrypto, -lcrypto
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/bn.h>
.Ve
.Vb 2
\& int BN_zero(BIGNUM *a);
\& int BN_one(BIGNUM *a);
.Ve
.Vb 1
\& BIGNUM *BN_value_one(void);
.Ve
.Vb 2
\& int BN_set_word(BIGNUM *a, unsigned long w);
\& unsigned long BN_get_word(BIGNUM *a);
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fIBN_zero()\fR, \fIBN_one()\fR and \fIBN_set_word()\fR set \fBa\fR to the values 0, 1 and
\&\fBw\fR respectively.  \fIBN_zero()\fR and \fIBN_one()\fR are macros.
.PP
\&\fIBN_value_one()\fR returns a \fB\s-1BIGNUM\s0\fR constant of value 1. This constant
is useful for use in comparisons and assignment.
.PP
\&\fIBN_get_word()\fR returns \fBa\fR, if it can be represented as an unsigned
long.
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fIBN_get_word()\fR returns the value \fBa\fR, and 0xffffffffL if \fBa\fR cannot
be represented as an unsigned long.
.PP
\&\fIBN_zero()\fR, \fIBN_one()\fR and \fIBN_set_word()\fR return 1 on success, 0 otherwise.
\&\fIBN_value_one()\fR returns the constant.
.SH "BUGS"
.IX Header "BUGS"
Someone might change the constant.
.PP
If a \fB\s-1BIGNUM\s0\fR is equal to 0xffffffffL it can be represented as an
unsigned long but this value is also returned on error.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
bn(3), BN_bn2bin(3)
.SH "HISTORY"
.IX Header "HISTORY"
\&\fIBN_zero()\fR, \fIBN_one()\fR and \fIBN_set_word()\fR are available in all versions of
SSLeay and OpenSSL. \fIBN_value_one()\fR and \fIBN_get_word()\fR were added in
SSLeay 0.8.