Manual:BN zero(3)

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BN_zero, BN_one, BN_value_one, BN_set_word, BN_get_word - BIGNUM assignment operations


 #include <openssl/bn.h>

 int BN_zero(BIGNUM *a);
 int BN_one(BIGNUM *a);

 const BIGNUM *BN_value_one(void);

 int BN_set_word(BIGNUM *a, unsigned long w);
 unsigned long BN_get_word(BIGNUM *a);


BN_zero(), BN_one() and BN_set_word() set a to the values 0, 1 and w respectively. BN_zero() and BN_one() are macros.

BN_value_one() returns a BIGNUM constant of value 1. This constant is useful for use in comparisons and assignment.

BN_get_word() returns a, if it can be represented as an unsigned long.


BN_get_word() returns the value a, and 0xffffffffL if a cannot be represented as an unsigned long.

BN_zero(), BN_one() and BN_set_word() return 1 on success, 0 otherwise. BN_value_one() returns the constant.


Someone might change the constant.

If a BIGNUM is equal to 0xffffffffL it can be represented as an unsigned long but this value is also returned on error.


bn(3), BN_bn2bin(3)


BN_zero(), BN_one() and BN_set_word() are available in all versions of SSLeay and OpenSSL. BN_value_one() and BN_get_word() were added in SSLeay 0.8.

BN_value_one() was changed to return a true const BIGNUM * in OpenSSL 0.9.7.