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Author Topic: Hex2Int() example  (Read 1849 times)

Offline TimoVJL

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Hex2Int() example
« on: May 02, 2016, 06:27:56 pm »
Ispired by masm32 forum topic here
Code: [Select]
int Hex2Int(char *s)
{
int n = 0;
unsigned char ch;
while (*s) {
ch = *s - '0';
if (ch >= 49 && ch <= 55) ch -= 39; // 'a' - '0'
else if (ch >= 17 && ch <= 22) ch -= 7; // 'A' - '0'
else if (ch < 0 || ch > 16) break;
n = n<<4;
n += ch;
s++;
}
return n;
}
« Last Edit: May 07, 2016, 09:04:27 am by TimoVJL »
May the source be with you

Offline jj2007

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Re: Hex2Int() example
« Reply #1 on: May 07, 2016, 08:37:52 am »
Hi Timo,
Does this work for you? I always get zero...

Code: [Select]
#include <stdio.h>

#pragma warn(disable:2216)    // retval never used
#pragma warn(disable:2007)    // assembly not portable
#pragma warn(disable:2018)    // _getch
#pragma comment(linker, "/subsystem:console" )

int Hex2Int(char *s)
{
int n = 0;
unsigned char ch;
// _asm int 3;
while (*s) {
ch = *s - '0'; /// <- sure?
if (ch >= 49 && ch <= 55) ch -= 39; // 'a' - '0'
else if (ch >= 17 && ch <= 22) ch -= 7; // 'A' - '0'
else break;
n = n<<4;
n += ch;
s++;
}
return n;
}
int main(void) {
  printf("%i\n", Hex2Int("123h"));
  _getch();
}

Offline TimoVJL

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Re: Hex2Int() example
« Reply #2 on: May 07, 2016, 09:06:45 am »
My mistake :(
value check should be
Code: [Select]
...
else if (ch < 0 || ch > 16) break;
...
not
Code: [Select]
else break;
May the source be with you