PERLCLIB

PERLCLIB

NAME DESCRIPTION SEE ALSO

NAME

perlclib - Internal replacements for standard C library functions

DESCRIPTION

One thing Perl porters should note is that perl doesn't tend to use that much of the C standard library internally; you'll see very little use of, for example, the 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.

Conventions

In the following tables:

t

is a type.

p

is a pointer.

n

is a number.

s

is a string.

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

File Operations

Instead of the stdio.h functions, you should use the Perl abstraction layer. Instead of FILE* types, you need to be handling PerlIO* types. Don't forget that with the new PerlIO layered I/O abstraction FILE* types may not even be available. See also the 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)

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 fread and 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 fgets; one should use sv_gets instead

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

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)

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 Copy and Move than used in memcpy and memmove.

Most of the time, though, you'll want to be dealing with SVs internally instead of raw 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 sv_catpvf and sv_catpvfn, combining concatenation with formatting.

Character Class Tests

There are two types of character class tests that Perl implements: one type deals in chars and are thus not Unicode aware (and hence deprecated unless you know you should use them) and the other type deal in UVs and know about Unicode properties. In the following table, c is a char, and 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)

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 scan_bin, scan_hex, and scan_oct functions in util.c for converting strings representing numbers in the respective bases into NVs.

In theory Strtol and 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)

Miscellaneous functions

You should not even want to use setjmp.h functions, but if you think you do, use the JMPENV stack in scope.h instead.

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

SEE ALSO

perlapi, perlapio, perlguts