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=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 thatmuch 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 Perltends to reimplement or abstract standard library functions, so that weknow exactly how they're going to operate.
This is a reference card for people who are familiar with the C libraryand who want to do things the Perl way; to tell them which functionsthey 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 abstractionlayer. 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 slightlydifferent 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 usedin C<memcpy> and C<memmove>.
Most of the time, though, you'll want to be dealing with SVs internallyinstead 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>, combiningconcatenation with formatting.
=head2 Character Class Tests
There are two types of character class tests that Perl implements: onetype deals in C<char>s and are thus B<not> Unicode aware (and hencedeprecated unless you B<know> you should use them) and the other typedeal in C<UV>s and know about Unicode properties. In the followingtable, 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 inF<util.c> for converting strings representing numbers in the respectivebases into C<NV>s.
In theory C<Strtol> and C<Strtoul> may not be defined if the machine perl isbuilt on doesn't actually have strtol and strtoul. But as those 2functions are part of the 1989 ANSI C spec we suspect you'll find themeverywhere 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 youthink 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>
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