convert a double keeping msb ?

[DanSteph]

hello all,

I have a problem, I have a DOUBLE value like that

4065 4000 0000 0000

and I want to convert it to a DWORD like that:
4065 4000

if I do result=(DWORD)M yDouble it end with AA(170)
wich I don't want.

Believe me or not but I spent 4 hours on this,
I cannot shift the bits, the compiler complaint with double,
it say: "bad left operand" "bad right operand" while it work
well with DWORD.

I'm puzzled, any help appreciated (VC++ 5.0)

Dan

[marbac]

DanSteph wrote:

hello all,

I have a problem, I have a DOUBLE value like that

4065 4000 0000 0000

and I want to convert it to a DWORD like that:
4065 4000

if I do result=(DWORD)M yDouble it end with AA(170)
wich I don't want.

Believe me or not but I spent 4 hours on this,
I cannot shift the bits, the compiler complaint with double,
it say: "bad left operand" "bad right operand" while it work
well with DWORD.

Hi, maybe this can help (used union to split 4 bytes into 2x2 bytes:

#include <iostream>
using std::cout;
using std::endl;

union mysplit {
unsigned int d;
unsigned short int i [2];
};

void splitme (unsigned int myint, unsigned short int &low, unsigned
short int &high) {

mysplit temp;
temp.d=myint;
low=temp.i[0];
high=temp.i[1];
}

int main () {
unsigned short int testint1, testint2;
unsigned int testint = 2864434397;

//AA BB CC DD ... BUT COMPILER WARNS (C90 compatible only)
//is just for testing

splitme (testint, testint1, testint2);
cout << testint1 << " ; " << testint2 << endl;
/* testint1: CCDD = 52445,
testint2: AABB = 43707 */

return 0;
}

regards marbac

[marbac]

DanSteph wrote:

hello all,

I have a problem, I have a DOUBLE value like that

4065 4000 0000 0000

and I want to convert it to a DWORD like that:
4065 4000

Hi, maybe this can help (used union to split 4 bytes into 2x2 bytes)
But i did it with int and short int:

#include <iostream>
using std::cout;
using std::endl;

union mysplit {
unsigned int d;
unsigned short int i [2];
};

void splitme (unsigned int myint, unsigned short int &low, unsigned
short int &high) {

mysplit temp;
temp.d=myint;
low=temp.i[0];
high=temp.i[1];
}

int main () {
unsigned short int testint1, testint2;
unsigned int testint = 2864434397;

//AA BB CC DD ... BUT COMPILER WARNS (C90 compatible only)
//is just for testing

splitme (testint, testint1, testint2);
cout << testint1 << " ; " << testint2 << endl;
/* testint1: CCDD = 52445,
testint2: AABB = 43707 */

return 0;
}

regards marbac

[marbac]

DanSteph wrote:

hello all, Believe me or not but I spent 4 hours on this,
I cannot shift the bits, the compiler complaint with double,
it say: "bad left operand" "bad right operand" while it work
well with DWORD.

Hi, maybe this can help (used union to split 4 bytes into 2x2 bytes)
But i did it with int and short int.
#include <iostream>
using std::cout;
using std::endl;

union mysplit {
unsigned int d;
unsigned short int i [2];
};

void splitme (unsigned int myint, unsigned short int &low, unsigned
short int &high) {

mysplit temp;
temp.d=myint;
low=temp.i[0];
high=temp.i[1];
}

int main () {
unsigned short int testint1, testint2;
unsigned int testint = 2864434397;

//AA BB CC DD ... BUT COMPILER WARNS (C90 compatible only)
//is just for testing

splitme (testint, testint1, testint2);
cout << testint1 << " ; " << testint2 << endl;
/* testint1: CCDD = 52445,
testint2: AABB = 43707 */

return 0;
}
I hope that i understood you correctly.

double has a sign, "mantisse" and an exponent ... maybe you want to
extract those?

regards marbac?