Difference between revisions of "Truxton file seek"
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=Syntax= | =Syntax= | ||
| − | < | + | <source lang="C"> |
int64_t truxton_file_seek( uint64_t file_handle, int64_t distance, int whence ); | int64_t truxton_file_seek( uint64_t file_handle, int64_t distance, int whence ); | ||
| − | </ | + | </source> |
=Parameters= | =Parameters= | ||
| Line 15: | Line 15: | ||
==<code>whence</code>== | ==<code>whence</code>== | ||
Where to seek from. | Where to seek from. | ||
| − | + | * <code>SEEK_SET</code> - 0 - the beginning of the file | |
| − | + | * <code>SEEK_CUR</code> - 1 - the current read offset | |
| − | + | * <code>SEEK_END</code> - 2 - the end of the file | |
These values mimic standard C library's [https://www.ibm.com/support/knowledgecenter/en/ssw_ibm_i_72/apis/lseek.htm lseek()] whence values. | These values mimic standard C library's [https://www.ibm.com/support/knowledgecenter/en/ssw_ibm_i_72/apis/lseek.htm lseek()] whence values. | ||
| Line 25: | Line 25: | ||
=Sample= | =Sample= | ||
| − | < | + | <source lang="C" highlight="10"> |
| − | int does_file_have_deep_philosophical_meaning(uint64_t truxton) | + | int does_file_have_deep_philosophical_meaning( uint64_t truxton ) |
{ | { | ||
| − | uint64_t file = truxton_file_open_id(truxton, "5ed3aeb7-3da4-5f5c-8c8f-af5200000000"); | + | uint64_t file = truxton_file_open_id( truxton, "5ed3aeb7-3da4-5f5c-8c8f-af5200000000" ); |
if ( file != 0 ) | if ( file != 0 ) | ||
{ | { | ||
| − | return(0); | + | return( 0 ); |
} | } | ||
| − | truxton_file_seek(file, 42, | + | truxton_file_seek( file, 42, SEEK_SET ); |
| − | int64_t read_position = truxton_file_tell(file); | + | int64_t read_position = truxton_file_tell( file ); |
| − | truxton_file_close(file); | + | truxton_file_close( file ); |
| − | truxton_file_free(file); | + | truxton_file_free( file ); |
if ( read_position == 42 ) | if ( read_position == 42 ) | ||
{ | { | ||
| − | return(1); | + | return( 1 ); |
} | } | ||
| − | return(0) | + | return( 0 ) |
} | } | ||
| − | </ | + | </source> |
Latest revision as of 17:34, 10 February 2021
This allows you to alter the offset into the opened file where the next read will take place.
Syntax
int64_t truxton_file_seek( uint64_t file_handle, int64_t distance, int whence );
Parameters
file_handle
The handle created by the truxton_file_open_id or truxton_file_open_md5 call.
distance
The number of bytes to move from whence
whence
Where to seek from.
SEEK_SET- 0 - the beginning of the fileSEEK_CUR- 1 - the current read offsetSEEK_END- 2 - the end of the file
These values mimic standard C library's lseek() whence values.
Return value
The offset into the file where the next byte will be read from.
Sample
int does_file_have_deep_philosophical_meaning( uint64_t truxton )
{
uint64_t file = truxton_file_open_id( truxton, "5ed3aeb7-3da4-5f5c-8c8f-af5200000000" );
if ( file != 0 )
{
return( 0 );
}
truxton_file_seek( file, 42, SEEK_SET );
int64_t read_position = truxton_file_tell( file );
truxton_file_close( file );
truxton_file_free( file );
if ( read_position == 42 )
{
return( 1 );
}
return( 0 )
}
