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. CCoonnvveennttiioonnss 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. FFiillee OOppeerraattiioonnss 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" docu-
mentation for more information about the following functions: Instead Of: Use: stdin PerlIOstdin() stdout PerlIOstdout() stderr PerlIOstderr() fopen(fn, mode) PerlIOopen(fn, mode) freopen(fn, mode, stream) PerlIOreopen(fn, mode, perlio) (Deprecated) fflush(stream) PerlIOflush(perlio) fclose(stream) PerlIOclose(perlio) FFiillee IInnppuutt aanndd OOuuttppuutt Instead Of: Use: fprintf(stream, fmt, ...) PerlIOprintf(perlio, fmt, ...) [f]getc(stream) PerlIOgetc(perlio) [f]putc(stream, n) PerlIOputc(perlio, n) ungetc(n, stream) PerlIOungetc(perlio, n) Note that the PerlIO equivalents of "fread" and "fwrite" are slightly different from their C library counterparts: fread(p, size, n, stream) PerlIOread(perlio, buf, numbytes) fwrite(p, size, n, stream) PerlIOwrite(perlio, buf, numbytes) fputs(s, stream) PerlIOputs(perlio, s) There is no equivalent to "fgets"; one should use "svgets" instead: fgets(s, n, stream) svgets(sv, perlio, append) FFiillee PPoossiittiioonniinngg Instead Of: Use: feof(stream) PerlIOeof(perlio) fseek(stream, n, whence) PerlIOseek(perlio, n, whence) rewind(stream) PerlIOrewind(perlio) fgetpos(stream, p) PerlIOgetpos(perlio, sv) fsetpos(stream, p) PerlIOsetpos(perlio, sv) ferror(stream) PerlIOerror(perlio) clearerr(stream) PerlIOclearerr(perlio) MMeemmoorryy MMaannaaggeemmeenntt aanndd SSttrriinngg HHaannddlliinngg 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) memset(dst, 0, n * sizeof(t)) Zero(dst, n, t) memzero(dst, 0) Zero(dst, n, char) 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) svlen(sv) strcpy(dt, src) svsetpv(sv, s) strncpy(dt, src, n) svsetpvn(sv, s, n) strcat(dt, src) svcatpv(sv, s) strncat(dt, src) svcatpvn(sv, s) sprintf(s, fmt, ...) svsetpvf(sv, fmt, ...) Note also the existence of "svcatpvf" and "svvcatpvfn", combining concatenation with formatting. Sometimes instead of zeroing the allocated heap by using Newz() you should consider "poisoning" the data. This means writing a bit patterninto it that should be illegal as pointers (and floating point num-
bers), and also hopefully surprising enough as integers, so that any code attempting to use the data without forethought will break sooner rather than later. Poisoning can be done using the Poison() macro, which has similar arguments as Zero(): Poison(dst, n, t) CChhaarraacctteerr CCllaassss TTeessttss There are two types of character class tests that Perl implements: onetype deals in "char"s and are thus nnoott Unicode aware (and hence depre-
cated unless you kknnooww you should use them) and the other type deal in "UV"s 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) isALNUMuni(u) isalpha(c) isALPHA(c) isALPHAuni(u) iscntrl(c) isCNTRL(c) isCNTRLuni(u) isdigit(c) isDIGIT(c) isDIGITuni(u) isgraph(c) isGRAPH(c) isGRAPHuni(u) islower(c) isLOWER(c) isLOWERuni(u) isprint(c) isPRINT(c) isPRINTuni(u) ispunct(c) isPUNCT(c) isPUNCTuni(u) isspace(c) isSPACE(c) isSPACEuni(u) isupper(c) isUPPER(c) isUPPERuni(u) isxdigit(c) isXDIGIT(c) isXDIGITuni(u) tolower(c) toLOWER(c) toLOWERuni(u) toupper(c) toUPPER(c) toUPPERuni(u) stdlib.h ffuunnccttiioonnss 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 "grokbin", "grokhex", and "grokoct" functions in numeric.c for converting strings representing numbers in the respective bases into "NV"s. 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((Randseedt)n); PLsrandcalled = TRUE; } exit(n) myexit(n) system(s) Don't. Look at ppsystem or use mypopen getenv(s) PerlEnvgetenv(s) setenv(s, val) myputenv(s, val) MMiisscceellllaanneeoouuss ffuunnccttiioonnss You should not even wwaanntt 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"perl v5.8.6 2004-11-05 PERLCLIB(1)