# convert from a binary number to a hex

Let's say I build a char array of size 24.

char test[24];

and I want to fill this with 0's and 1's.  For example:

1010111100000000  etc.

Now I want to parse the first four characters and treat them as a binary number.  Continuing the example:

1010

Now I want to convert that to the hex equivilant:

1010 would equal A

How would I do this.

F

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Commented:
To convert a number to an ASCII string representing its value in binary, you can use the binary AND (&) operator to test the value of the bits int the number.  For example.

Cnv2Bin(int Num,char *Dst,int Len)
{
int Msk = 1;

Dst += Len-1;
for (int i = 0; i < Len; ++i)
{
char Dig = Num & Msk?'1':'0';
*Dst-- = Dig;
Msg <<= 1;
}
}

continues
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Commented:
To convert an strign representing a binary number to a strign representing a Hex number, it is best to convert each nibble of the number binary representation to an integer.  To do this

int
CnvBin2Int(char *Src) // -> 4 character string of the binary number to be converted.
{
int Num = 0;

for (int i =0; i < 4; ++i)
{
Num <<= 1;
if (*Src++ == '1')
++Num;
}
return Num;
}

Then to convert a binary reprentation string to a HEX representation string you would so somethign like

void CnvBin2Hex(char *Dst,char *Src,int Len)
{
for (int i = 0; i < Len; ++i)
{
int Nibble = CnvBin2Int(Src);
Char Digit;

if (Nibble < 10)
Digit = '0' + Nibble;
else
Digit = 'A' + Nibble;
*Dst++ = Digit;
Src += 4;
}
}

Let me know if you have any questions.
0
Author Commented:
Thanks a lot.
0
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