convert a binary into decimal

[QQ]

Hello

unsigned char a;

the a[0-3] represents a 4-bit binary,
a[4-6] represents another 3-bit binary.

I'd like to convert a[0-3] into a decimal.
For instance if {a[3] a[2] a[1] a[0}}= {0 1 0 1] the decimal should be
5

My program is like

if((a && 0x00)==1) return 0;
else if (a&& 0x01)==1) return 1;
.....

Is there any simpler way for it?

Thanks a lot!

[Nils O. Selåsdal]

QQ wrote:

Hello

unsigned char a;

the a[0-3] represents a 4-bit binary,
return a & 0xf;
a[4-6] represents another 3-bit binary.

return (a >> 4) & 0x7;

[pemo]

QQ wrote:

Hello

unsigned char a;

the a[0-3] represents a 4-bit binary,
a[4-6] represents another 3-bit binary.

I'd like to convert a[0-3] into a decimal.
For instance if {a[3] a[2] a[1] a[0}}= {0 1 0 1] the decimal should
be 5

My program is like

if((a && 0x00)==1) return 0;
else if (a&& 0x01)==1) return 1;
....

Is there any simpler way for it?

Thanks a lot!

0-3 = a & 0x0F;
4-6 = (a & 0x70) >> 4;

--
==============
Not a pedant
==============

[Martin Ambuhl]

QQ wrote:

unsigned char a; the a[0-3] represents a 4-bit binary,
a[4-6] represents another 3-bit binary. I'd like to convert a[0-3] into a decimal.
For instance if {a[3] a[2] a[1] a[0}}= {0 1 0 1] the decimal should be
5

My program is like

if((a && 0x00)==1) return 0;
else if (a&& 0x01)==1) return 1;
I don't understand how the above can do what you want.
Is there any simpler way for it?

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <limits.h>

int main(void)
{
unsigned char a;
int i;
srand(time(0));
for (i = 0; i < 4; i++) {
a = (unsigned) rand();
printf
("a = %3u (%#03o, %#02x), first 4 bits=%u,"
" next 3 bits=%u\n",
a, a, a, a >> (CHAR_BIT - 4), 07 & (a >> (CHAR_BIT - 7)));
}
return 0;
}
a = 186 (0272, 0xba), first 4 bits=11, next 3 bits=5
a = 171 (0253, 0xab), first 4 bits=10, next 3 bits=5
a = 19 (023, 0x13), first 4 bits=1, next 3 bits=1
a = 98 (0142, 0x62), first 4 bits=6, next 3 bits=1

[Barry Schwarz]

On 22 Mar 2006 09:45:53 -0800, "QQ" <ju****@yahoo.com> wrote:

Hello

unsigned char a;

the a[0-3] represents a 4-bit binary,
a[4-6] represents another 3-bit binary.

I'd like to convert a[0-3] into a decimal.
For instance if {a[3] a[2] a[1] a[0}}= {0 1 0 1] the decimal should be
5

My program is like

if((a && 0x00)==1) return 0;
The if is guaranteed to always be false. Anything && 0 is always
false.
else if (a&& 0x01)==1) return 1;

This is no different than if(a). Did you perhaps mean (a & 0x01)?

Apparently your unsigned char holds 0 or 1 as opposed to '0' and '1'.
In this case, you can compute
num1 = a[3]*8 + a[2]*4 + a[1]*2 + a[0];
and
num2 = a[6]*4 + a[5]*2 + a[4];
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