Truxton file get signature - Revision history

Sam at 08:46, 13 February 2021

2021-02-13T08:46:48Z

Sam at 16:10, 7 December 2020

2020-12-07T16:10:20Z

Sam: /* Sample */

2020-12-07T16:10:01Z

Sample

Sam at 20:36, 23 November 2020

2020-11-23T20:36:46Z

Sam: Created page with "This retrieves the signature of the file's contents. It corresponds to the `Signature` column of the `File` table. =Syntax=
2020-06-21T11:42:23Z

Created page with "This retrieves the signature of the file's contents. It corresponds to the <code>Signature</code> column of the <code> File</code> table. =Syntax= <syntaxhigh..."

New page
This retrieves the signature of the file's contents.
It corresponds to the <code>Signature</code> column of the <code>[[File Table | File]]</code> table.

=Syntax=
<syntaxhighlight lang="C">
uint32_t truxton_file_get_signature( uint64_t file_handle );
</syntaxhighlight>

=Parameters=
==<code>file_handle</code>==
The handle created by the [[truxton_file_open_id]] or [[truxton_file_open_md5]] call.

=Return value=
The first four bytes of the file's contents as an integer.

=Sample=

<syntaxhighlight lang="C" highlight="10">
void print_it(uint64_t truxton)
{
uint64_t file = truxton_file_open_md5(truxton, "9ec8fb6095c35eff2b236863b7caaf10");

if ( file != 0 )
{
return;
}

uint32_t signature = truxton_file_get_signature( file );

printf( "Signature is %08" PRIX32 "\n", signature );

truxton_file_free( file );
}
</syntaxhighlight>

Note, the <code>PRIu64</code> in the sample code above is the new standard way of [https://en.wikipedia.org/wiki/C_data_types#Printf_and_scanf_format_specifiers formatting] a 64-bit integer in C.
Over the years, different compilers on different operating systems used different format specifiers for things, these <code>PRI</code> macros, along with some tricky string concatenation the compilers perform for you, allow you to maintain a single code base without a bunch of macro magic.