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Full Discussion: Why this const variable is not changing even after applying const_cast?
Top Forums Programming Why this const variable is not changing even after applying const_cast? Post 302518211 by royalibrahim on Friday 29th of April 2011 12:13:29 AM
Old 04-29-2011
Quote:
Originally Posted by shamrock
What makes you think it should change a "constant"...i is a constant and the pointer is to a constant which shouldnt change i.
When I access it through a pointer after suppressing const'ness, I could change the value through the pointer, but still 'i' remains the same, (i.e)

Code:
int main() {
    const int i = 10;
    int *p = const_cast <int*> (&i);
    *p = 11;
    cout << *p << "  " << i << endl;  // Ans: 11  10

    *(const_cast<int*>(&i)) = 11;
    cout << i << endl;  // Ans: 10

    *(const_cast<int*>(p)) = 12;
    cout << *p << "  " << i << endl;  // Ans: 12  10
}

I compiled the above code using gcc compiler. What is really confusing me is, where the pointer '*p' is pointing to so that it is printing the value that is not stored in 'i'?
 

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LEARN ABOUT NETBSD

bn_zero

BN_zero(3)							      OpenSSL								BN_zero(3)

NAME

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

LIBRARY

       libcrypto, -lcrypto

SYNOPSIS

	#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);

DESCRIPTION

       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.

RETURN VALUES

       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.

BUGS

       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.

SEE ALSO

       openssl_bn(3), BN_bn2bin(3)

HISTORY

       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.

1.0.1i								    2009-07-20								BN_zero(3)
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