converting ascii to its decimal codes

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December 19th, 2002, 05:17 AM

seb_sikora

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converting ascii to its decimal codes

Hi

Ive been looking for some c code to convert an ascii character, to its decimal code. I cant find anything in any of the books i have, and havent had any luck with google.

In Quick Basic, there is a simple command to do this, just the command ASC using the structure

ASC("A") gives the decimal value of A, 65.

Any help would be much appreciated.

Thanks

Seb

December 19th, 2002, 09:29 AM

Analyser

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You don't need a function to get the ASCII value of a character. The expression 'A' simply evaluates to 65. Hence, to print 'B', you could use 'A' + 1:

Code:

print("%c\n", 'A' + 1);

You can even do this:

Code:

print("%d\n", 'Z' - 'A');

which will print 25.

Hope this helps.

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December 19th, 2002, 10:29 AM

seb_sikora

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thanks!

Cheers, that worked ok!

If i have any more trouble, ill be back

Take care

Seb

December 19th, 2002, 10:33 AM

amitchd

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ascii val

Getting an ascii code of a character is quite easy in c++. There are many ways... Suppose if you want to print the ascii code you may just do as follows..

Code:

char a='B';
printf("%c=%i",a,a);

so the output would be B=66.

But.. if you want to get the ascii value in some variable

Code:

char a='B';
int as=a;

so 66 is stored to as ... this is implicit conversion..

you may also implement this with a function

Code:

int asc_ii(char a)
{    int k=a; return a;
}

]

Hope this helps...

February 13th, 2003, 04:57 AM

Hotkey

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Hmmm, i've read this threat to find out how i can get the ascii code for a character just to find out that it doesn't works for me completely.
So far i used the following method to reveal the ascii code :

Code:

char asc='G';
int code=asc;

I need this to read out a binary file. Now i got the Byte "AA" - which should be resolved to the ascii code 170 (dezimal).
But my above code gives me a (-86) - so i can't resolve the Hexadezimal value with this one.

Can anyone help me out with this ?

Thanks in advance

Hotkey

February 13th, 2003, 09:41 AM

dwise1_aol

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Quote:

Originally posted by Hotkey
Hmmm, i've read this threat to find out how i can get the ascii code for a character just to find out that it doesn't works for me completely.
So far i used the following method to reveal the ascii code :

Code:

char asc='G'; int code=asc;

I need this to read out a binary file. Now i got the Byte "AA" - which should be resolved to the ascii code 170 (dezimal).
But my above code gives me a (-86) - so i can't resolve the Hexadezimal value with this one.

Can anyone help me out with this ?

Thanks in advance

Hotkey

Obtaining the ASCII code for a given character is one thing, but converting an ASCII representation of a hex value to the value being represented is a different matter altogether.

What you need is the hexadecimal equivalent of atoi(). Fortunately, I've already written one:

Code:

// uint is unsigned int
// ulong is unsigned long

int hexval(char c)
{    
   int n;
   
   if ((c>='0') && (c<='9'))
      n = c - '0';
   else if ((c>='A') && (c<='F'))
      n = c - 'A' + 10;
   else if ((c>='a') && (c<='f'))
      n = c - 'a' + 10;
   else 
      n = 0;
   return n;
}

                                      
uint htoui(char *s)
{
   char *cp; 
   uint n;
      
   n = 0;
   for (cp = s; (*cp != '\0') && ((*cp == ' ') || (*cp == '\t')); cp++);
   for ( ; (*cp != '\0') && isHex(*cp); cp++)
      n = ((n << 4) & 0xFFF0) + hexval(*cp);
   return n;
}


ulong htoul(char *s)
{
   char *cp; 
   ulong n;
      
   n = 0L;
   for (cp = s; (*cp != '\0') && ((*cp == ' ') || (*cp == '\t')); cp++);
   for ( ; (*cp != '\0') && isHex(*cp); cp++)
      n = ((n << 4) & 0xFFFFFFF0L) + hexval(*cp);
   return n;
}

That should help.

February 13th, 2003, 09:44 AM

dwise1_aol

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Oops! I thought that I had highlighted the isHex() function too.

isHex() is analogous to isdigit().

Code:

int isHex(char c)
{
   return ( ((c>='0') && (c<='9')) || ((c>='A') && (c<='F')) || 
            ((c>='a') && (c<='f')) ) ? 1 : 0;
}

BTW, thanks for the "code" tag.

February 14th, 2003, 05:38 PM

ngibsonau

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Heres a curve ball

what about

Code:


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

int htoi(char *str){
  unsigned int x;
  sscanf(str,"%2X",&x);
  return (int) x;
}

int main(int argc, char **argv)
{
  printf("%d\n", htoi("AA"));
  return 0;
}

As they say don't try to reinvent the wheel.

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ngibsonau

February 17th, 2003, 03:28 AM

Hotkey

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Many thanks 4 your help ! This is getting me into it again :-)
Greets
Hotkey

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