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pilar
Joined: 30 Jan 2008
Posts: 197
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| String Ascii to int |
 Posted: Tue Jan 29, 2013 4:50 pm |
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Hi, some one can help me...
I have a string ascii:
| Code: | Buffer[0] = 0x31;
Buffer[1] = 0x31;
Buffer[2] = 0x33;
Buffer[3] = 0x39; |
I should I do to get the equivalent: 4409 decimal?, I need this to do math |
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Mike Walne
Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK
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| Posted: Tue Jan 29, 2013 6:14 pm |
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There are 'C' functions for this, ATOI(), ATOL(), ATOI32.
Take your pick.
Mike
EDIT Your ASCII values convert to 1139 ! |
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pilar
Joined: 30 Jan 2008
Posts: 197
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| Posted: Tue Jan 29, 2013 6:17 pm |
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 Maybe I misspoke, I'm getting for the Uart the Ascii characters 1,1,3 and 9, representing a hexadecimal number 0x1139, these characters must be equivalent to 4409 in decimal value, my problem is that I have the any idea how to make their equivalence ... : |
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Mike Walne
Joined: 19 Feb 2004
Posts: 1785
Location: Boston Spa UK
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| Posted: Tue Jan 29, 2013 6:30 pm |
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To do it by hand:-
1) Convert first digit from HEX to decimal. //1
2) Multiply by 16. // 16
3) Convert second digit to HEX. // 1
4) Add results from 2 and 3 together. // 17
5) Multiply new result by 16. // 272
6) Continue until you run out of digits.
Mike |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Tue Jan 29, 2013 7:03 pm |
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Here is a 16-bit version of a function that I used to use for this:
| Code: |
#include <18F4520.h>
#fuses INTRC_IO,NOWDT,PUT,BROWNOUT,NOLVP
#use delay(clock=4M)
#use rs232(baud=9600, UART1, ERRORS)
#include <ctype.h>
//-------------------------------------------------
// Ascii to unsigned long -
// Converts a string of 1 to 4 ascii hex characters to an
// unsigned long (16-bit) value.
int16 axtoul(char *ptr)
{
char i, temp;
int16 result;
result = 0;
for(i = 0; i < 4; i++) // Convert a maximum of 4 hex digits
{
temp = toupper(*ptr++); // Get the char. Convert to upper case
if(isxdigit(temp) == FALSE) // Is ascii char a hex digit ?
break; // Break if not
temp -= '0'; // Convert the char to binary
if(temp > 9)
temp -= 7;
result <<= 4; // shift existing value left 1 nybble
result |= temp; // Then combine it with new nybble
}
return(result);
}
//================================
void main(void)
{
int16 result;
int8 buffer[] = "1139"; // Hex value
result = axtoul(buffer);
printf("result = %lu \r", result);
while(1);
} |
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pilar
Joined: 30 Jan 2008
Posts: 197
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| Posted: Tue Jan 29, 2013 7:16 pm |
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 Thank you.... |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Wed Jan 30, 2013 7:39 am |
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not to be a nit picker but if it is really a string , i would include
the way you want to handle it, "buffer " does technically NOT contain a "string" at all, unless every instance is limited to 4 bytes by code.
just my 2 cents |
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