Programming Perl in C

Copy(src, dst, 1024, char);      // copy 1024 bytes from src to dst

Move(buf, buf + 10, 1024, char); // copy 1024 bytes down 10 bytes in buf

IO Operations

The Perl API defines wrappers around most of the stdio functions you know and 

love. These wrappers all begin with PerlIO_ and are usually followed by the name 

of the stdio function they wrap. The perlapio documentation included with Perl 

contains a complete listing the available functions and their signatures. Be aware 

that in some cases the Perl developers have  fixed  parameter ordering and function 

names while wrapping stdio functions.

The principal difference between stdio's functions and the PerlIO set is that 

stdio uses the FILE* type to represent file handles, whereas the Perl API uses 

PerlIO*. For example, to open a log file and print a line to it, you might use code 

like this:

PerlIO *fh = PerlIO_open("/tmp/my.log", "a"); // open logfile in append mode

if (!fh) croak("Unable to open /tmp/my.log"); // check that open succeeded

PerlIO_printf(fh, "Log test...\n");           // print a test line

PerlIO_close(fh);                             // close the file

Notice that the PerlIO_printf()is actually a wrapper around fprintf(). For 

printf() functionality, use PerlIO_stdoutf():

PerlIO_stdoutf("Hello world!\n");

The Perl API also provides functions for interfacing the PerlIO model with 

existing stdio systems. For example, you can translate between PerlIO* and FILE*

file handles with the PerlIO_import and PerlIO_export functions:

PerlIO *pfh;

FILE   *fh;

pfh = PerlIO_open("some.file", "r");  // open a PerlIO handle

fh  = PerlIO_export(pfh, 0);          // export to a FILE *

// ... do some stdio work with fh

PerlIO_releaseFILE(pfh, fh);          // release fh mapping to pfh

PerlIO_close(pfh);

The Perl IO API is currently under development, and it is expected that in the 

near future Perl will cut its ties to stdio entirely. At that point, only C modules that 

use the PerlIO interface will work correctly. As such, it is important to get used to 

using PerlIO now.

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