=head1 NAME

perlclib - Internal replacements for standard C library functions

=head1 DESCRIPTION

One thing Perl porters should note is that F<perl> doesn't tend to use that

much of the C standard library internally; you'll see very little use of,

for example, the F<ctype.h> functions in there. This is because Perl

tends to reimplement or abstract standard library functions, so that we

know exactly how they're going to operate.

This is a reference card for people who are familiar with the C library

and who want to do things the Perl way; to tell them which functions

they ought to use instead of the more normal C functions.

=head2 Conventions

In the following tables:

=over 3

=item C<t>

is a type.

=item C<p>

is a pointer.

=item C<n>

is a number.

=item C<s>

is a string.

=back

C<sv>, C<av>, C<hv>, etc. represent variables of their respective types.

=head2 File Operations

Instead of the F<stdio.h> functions, you should use the Perl abstraction

layer. Instead of C<FILE*> types, you need to be handling C<PerlIO*>

types. Don't forget that with the new PerlIO layered I/O abstraction

C<FILE*> types may not even be available. See also the C<perlapio>

documentation for more information about the following functions:

Instead Of: Use:

stdin PerlIO_stdin()

stdout PerlIO_stdout()

stderr PerlIO_stderr()

fopen(fn, mode) PerlIO_open(fn, mode)

freopen(fn, mode, stream) PerlIO_reopen(fn, mode, perlio) (Deprecated)

fflush(stream) PerlIO_flush(perlio)

fclose(stream) PerlIO_close(perlio)

=head2 File Input and Output

Instead Of: Use:

fprintf(stream, fmt, ...) PerlIO_printf(perlio, fmt, ...)

[f]getc(stream) PerlIO_getc(perlio)

[f]putc(stream, n) PerlIO_putc(perlio, n)

ungetc(n, stream) PerlIO_ungetc(perlio, n)

Note that the PerlIO equivalents of C<fread> and C<fwrite> are slightly

different from their C library counterparts:

fread(p, size, n, stream) PerlIO_read(perlio, buf, numbytes)

fwrite(p, size, n, stream) PerlIO_write(perlio, buf, numbytes)

fputs(s, stream) PerlIO_puts(perlio, s)

There is no equivalent to C<fgets>; one should use C<sv_gets> instead:

fgets(s, n, stream) sv_gets(sv, perlio, append)

=head2 File Positioning

Instead Of: Use:

feof(stream) PerlIO_eof(perlio)

fseek(stream, n, whence) PerlIO_seek(perlio, n, whence)

rewind(stream) PerlIO_rewind(perlio)

fgetpos(stream, p) PerlIO_getpos(perlio, sv)

fsetpos(stream, p) PerlIO_setpos(perlio, sv)

ferror(stream) PerlIO_error(perlio)

clearerr(stream) PerlIO_clearerr(perlio)

=head2 Memory Management and String Handling

Instead Of: Use:

t* p = malloc(n) New(id, p, n, t)

t* p = calloc(n, s) Newz(id, p, n, t)

p = realloc(p, n) Renew(p, n, t)

memcpy(dst, src, n) Copy(src, dst, n, t)

memmove(dst, src, n) Move(src, dst, n, t)

memcpy/*(struct foo *) StructCopy(src, dst, t)

free(p) Safefree(p)

strdup(p) savepv(p)

strndup(p, n) savepvn(p, n) (Hey, strndup doesn't exist!)

strstr(big, little) instr(big, little)

strcmp(s1, s2) strLE(s1, s2) / strEQ(s1, s2) / strGT(s1,s2)

strncmp(s1, s2, n) strnNE(s1, s2, n) / strnEQ(s1, s2, n)

Notice the different order of arguments to C<Copy> and C<Move> than used

in C<memcpy> and C<memmove>.

Most of the time, though, you'll want to be dealing with SVs internally

instead of raw C<char *> strings:

strlen(s) sv_len(sv)

strcpy(dt, src) sv_setpv(sv, s)

strncpy(dt, src, n) sv_setpvn(sv, s, n)

strcat(dt, src) sv_catpv(sv, s)

strncat(dt, src) sv_catpvn(sv, s)

sprintf(s, fmt, ...) sv_setpvf(sv, fmt, ...)

Note also the existence of C<sv_catpvf> and C<sv_catpvfn>, combining

concatenation with formatting.

=head2 Character Class Tests

There are two types of character class tests that Perl implements: one

type deals in C<char>s and are thus B<not> Unicode aware (and hence

deprecated unless you B<know> you should use them) and the other type

deal in C<UV>s and know about Unicode properties. In the following

table, C<c> is a C<char>, and C<u> is a Unicode codepoint.

Instead Of: Use: But better use:

isalnum(c) isALNUM(c) isALNUM_uni(u)

isalpha(c) isALPHA(c) isALPHA_uni(u)

iscntrl(c) isCNTRL(c) isCNTRL_uni(u)

isdigit(c) isDIGIT(c) isDIGIT_uni(u)

isgraph(c) isGRAPH(c) isGRAPH_uni(u)

islower(c) isLOWER(c) isLOWER_uni(u)

isprint(c) isPRINT(c) isPRINT_uni(u)

ispunct(c) isPUNCT(c) isPUNCT_uni(u)

isspace(c) isSPACE(c) isSPACE_uni(u)

isupper(c) isUPPER(c) isUPPER_uni(u)

isxdigit(c) isXDIGIT(c) isXDIGIT_uni(u)

tolower(c) toLOWER(c) toLOWER_uni(u)

toupper(c) toUPPER(c) toUPPER_uni(u)

=head2 F<stdlib.h> functions

Instead Of: Use:

atof(s) Atof(s)

atol(s) Atol(s)

strtod(s, *p) Nothing. Just don't use it.

strtol(s, *p, n) Strtol(s, *p, n)

strtoul(s, *p, n) Strtoul(s, *p, n)

Notice also the C<scan_bin>, C<scan_hex>, and C<scan_oct> functions in

F<util.c> for converting strings representing numbers in the respective

bases into C<NV>s.

In theory C<Strtol> and C<Strtoul> may not be defined if the machine perl is

built on doesn't actually have strtol and strtoul. But as those 2

functions are part of the 1989 ANSI C spec we suspect you'll find them

everywhere by now.

int rand() double Drand01()

srand(n) { seedDrand01((Rand_seed_t)n);

PL_srand_called = TRUE; }

exit(n) my_exit(n)

system(s) Don't. Look at pp_system or use my_popen

getenv(s) PerlEnv_getenv(s)

setenv(s, val) my_putenv(s, val)

=head2 Miscellaneous functions

You should not even B<want> to use F<setjmp.h> functions, but if you

think you do, use the C<JMPENV> stack in F<scope.h> instead.

For C<signal>/C<sigaction>, use C<rsignal(signo, handler)>.

=head1 SEE ALSO

C<perlapi>, C<perlapio>, C<perlguts>