Member Avatar for sofianos

Can someone explains what specific "0x30" does in the decimal to binary function below:

void dec2bin(long decimal, char *binary)
{
int k = 0, n = 0;
int neg_flag = 0;
int remain;
char temp[80]; // take care of negative input
if (decimal < 0)
{
decimal = -decimal;
neg_flag = 1;
}
do
{
remain = decimal % 2;
decimal = decimal / 2; // whittle down decimal
temp[k++] = remain + 0x30; // makes characters 0 or 1
} while (decimal > 0);
if (neg_flag)
temp[k++] = '-'; // add back - sign
else
temp[k++] = ' '; // or space
while (k >= 0)
{
binary[n++] = temp; // reverse spelling
}
binary[n-1] = 0; // end with NULL
}

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  • Latest Post Latest Post by Rashakil Fol
Member Avatar for Ancient Dragon

0x30 is hexidecimal value of 48 decimal (use your scientific calculator to convert 30 hex to decimal). Adding 48 to a numeric digit will make it a printable digit -- see any ascii conversion chart.

Member Avatar for sofianos

i understand what you say but i still did not understant what it does in the specific function......:?:

Member Avatar for Ancient Dragon

temp variable is a character array. before adding the binary digit to temp the digits must be converted to one of the ascii characters '0' through '9'. for example: 1 + 48 = 49, and if you look at that ascii chart the number 49 is the letter '1'. Also note that the number 1 and the letter '1' are not the same thing.

Member Avatar for sofianos

Ohh! I see....Thanks a lot for the help! Keep up the good work.

THANKS!!!!!!!!!!!!!!!!!!!!!

Member Avatar for ~s.o.s~

Though it would have been simple if they had something like:

// more simple to understand and no need of keeping in mind the 
// ASCII equivalent of '0'
temp[k++] = remain + '0' ;
Member Avatar for Rashakil Fol

Also, more portable, since you're not making assumptions about character set.

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