Ascii to hexadecimal values

oulevon · 02-25-2006, 07:44 PM

Hello, I have to read in a Ascii file and manipulate the data in the file as numeric (hexadecimal) values instead of as characters. I was wondering if there was some sort of call in the C library to do this, or do I need to write something myself. So as an example, say I have the following text file:

Code:

This is a file.

I need to open this and retrieve the data and manipulate it as it's numeric ASCII values. The reason for this is because I've implemented an encryption algorithm, and I need to read in the values as bytes instead of as plain text. There may be a really easy way to do this, so before I attempted to create my own function, I thought I'd post this.

Thanks for any suggestions.

Dark_Helmet · 02-25-2006, 08:34 PM

It's already in hexadecimal values in memory. That's how the computer stores it.

So, if you want to read in the string as a sequence of 32-bit numbers (usually equivalent to four characters in the string), do this:

Code:

char     *sFileText;
unsigned  uNumericData;

...

for( chunk = 0; chunk < DATA_SIZE; chunk++ )
{
  // Typecast the string pointer to pretend it's pointing at an array of unsigneds
  // Add "chunk" to the pointer to get the offset for the next group of 4 bytes
  // Dereference the adjusted unsigned pointer to retrieve the data
  uNumericData = *((unsigned *)sFileText + chunk);

  // Process uNumericData
}

oulevon · 02-25-2006, 09:08 PM

Thanks for the suggestion. I'll give it a try.