1=head1 NAME 2 3perlclib - Internal replacements for standard C library functions 4 5=head1 DESCRIPTION 6 7One thing Perl porters should note is that F<perl> doesn't tend to use that 8much of the C standard library internally; you'll see very little use of, 9for example, the F<ctype.h> functions in there. This is because Perl 10tends to reimplement or abstract standard library functions, so that we 11know exactly how they're going to operate. 12 13This is a reference card for people who are familiar with the C library 14and who want to do things the Perl way; to tell them which functions 15they ought to use instead of the more normal C functions. 16 17=head2 Conventions 18 19In the following tables: 20 21=over 3 22 23=item C<t> 24 25is a type. 26 27=item C<p> 28 29is a pointer. 30 31=item C<n> 32 33is a number. 34 35=item C<s> 36 37is a string. 38 39=back 40 41C<sv>, C<av>, C<hv>, etc. represent variables of their respective types. 42 43=head2 File Operations 44 45Instead of the F<stdio.h> functions, you should use the Perl abstraction 46layer. Instead of C<FILE*> types, you need to be handling C<PerlIO*> 47types. Don't forget that with the new PerlIO layered I/O abstraction 48C<FILE*> types may not even be available. See also the C<perlapio> 49documentation for more information about the following functions: 50 51 Instead Of: Use: 52 53 stdin PerlIO_stdin() 54 stdout PerlIO_stdout() 55 stderr PerlIO_stderr() 56 57 fopen(fn, mode) PerlIO_open(fn, mode) 58 freopen(fn, mode, stream) PerlIO_reopen(fn, mode, perlio) (Dep- 59 recated) 60 fflush(stream) PerlIO_flush(perlio) 61 fclose(stream) PerlIO_close(perlio) 62 63=head2 File Input and Output 64 65 Instead Of: Use: 66 67 fprintf(stream, fmt, ...) PerlIO_printf(perlio, fmt, ...) 68 69 [f]getc(stream) PerlIO_getc(perlio) 70 [f]putc(stream, n) PerlIO_putc(perlio, n) 71 ungetc(n, stream) PerlIO_ungetc(perlio, n) 72 73Note that the PerlIO equivalents of C<fread> and C<fwrite> are slightly 74different from their C library counterparts: 75 76 fread(p, size, n, stream) PerlIO_read(perlio, buf, numbytes) 77 fwrite(p, size, n, stream) PerlIO_write(perlio, buf, numbytes) 78 79 fputs(s, stream) PerlIO_puts(perlio, s) 80 81There is no equivalent to C<fgets>; one should use C<sv_gets> instead: 82 83 fgets(s, n, stream) sv_gets(sv, perlio, append) 84 85=head2 File Positioning 86 87 Instead Of: Use: 88 89 feof(stream) PerlIO_eof(perlio) 90 fseek(stream, n, whence) PerlIO_seek(perlio, n, whence) 91 rewind(stream) PerlIO_rewind(perlio) 92 93 fgetpos(stream, p) PerlIO_getpos(perlio, sv) 94 fsetpos(stream, p) PerlIO_setpos(perlio, sv) 95 96 ferror(stream) PerlIO_error(perlio) 97 clearerr(stream) PerlIO_clearerr(perlio) 98 99=head2 Memory Management and String Handling 100 101 Instead Of: Use: 102 103 t* p = malloc(n) Newx(p, n, t) 104 t* p = calloc(n, s) Newxz(p, n, t) 105 p = realloc(p, n) Renew(p, n, t) 106 memcpy(dst, src, n) Copy(src, dst, n, t) 107 memmove(dst, src, n) Move(src, dst, n, t) 108 memcpy(dst, src, sizeof(t)) StructCopy(src, dst, t) 109 memset(dst, 0, n * sizeof(t)) Zero(dst, n, t) 110 memzero(dst, 0) Zero(dst, n, char) 111 free(p) Safefree(p) 112 113 strdup(p) savepv(p) 114 strndup(p, n) savepvn(p, n) (Hey, strndup doesn't 115 exist!) 116 117 strstr(big, little) instr(big, little) 118 strcmp(s1, s2) strLE(s1, s2) / strEQ(s1, s2) 119 / strGT(s1,s2) 120 strncmp(s1, s2, n) strnNE(s1, s2, n) / strnEQ(s1, s2, n) 121 122Notice the different order of arguments to C<Copy> and C<Move> than used 123in C<memcpy> and C<memmove>. 124 125Most of the time, though, you'll want to be dealing with SVs internally 126instead of raw C<char *> strings: 127 128 strlen(s) sv_len(sv) 129 strcpy(dt, src) sv_setpv(sv, s) 130 strncpy(dt, src, n) sv_setpvn(sv, s, n) 131 strcat(dt, src) sv_catpv(sv, s) 132 strncat(dt, src) sv_catpvn(sv, s) 133 sprintf(s, fmt, ...) sv_setpvf(sv, fmt, ...) 134 135Note also the existence of C<sv_catpvf> and C<sv_vcatpvfn>, combining 136concatenation with formatting. 137 138Sometimes instead of zeroing the allocated heap by using Newxz() you 139should consider "poisoning" the data. This means writing a bit 140pattern into it that should be illegal as pointers (and floating point 141numbers), and also hopefully surprising enough as integers, so that 142any code attempting to use the data without forethought will break 143sooner rather than later. Poisoning can be done using the Poison() 144macros, which have similar arguments to Zero(): 145 146 PoisonWith(dst, n, t, b) scribble memory with byte b 147 PoisonNew(dst, n, t) equal to PoisonWith(dst, n, t, 0xAB) 148 PoisonFree(dst, n, t) equal to PoisonWith(dst, n, t, 0xEF) 149 Poison(dst, n, t) equal to PoisonFree(dst, n, t) 150 151=head2 Character Class Tests 152 153There are several types of character class tests that Perl implements. 154The only ones described here are those that directly correspond to C 155library functions that operate on 8-bit characters, but there are 156equivalents that operate on wide characters, and UTF-8 encoded strings. 157All are more fully described in L<perlapi/Character classes> and 158L<perlapi/Character case changing>. 159 160The C library routines listed in the table below return values based on 161the current locale. Use the entries in the final column for that 162functionality. The other two columns always assume a POSIX (or C) 163locale. The entries in the ASCII column are only meaningful for ASCII 164inputs, returning FALSE for anything else. Use these only when you 165B<know> that is what you want. The entries in the Latin1 column assume 166that the non-ASCII 8-bit characters are as Unicode defines, them, the 167same as ISO-8859-1, often called Latin 1. 168 169 Instead Of: Use for ASCII: Use for Latin1: Use for locale: 170 171 isalnum(c) isALPHANUMERIC(c) isALPHANUMERIC_L1(c) isALPHANUMERIC_LC(c) 172 isalpha(c) isALPHA(c) isALPHA_L1(c) isALPHA_LC(u ) 173 isascii(c) isASCII(c) isASCII_LC(c) 174 isblank(c) isBLANK(c) isBLANK_L1(c) isBLANK_LC(c) 175 iscntrl(c) isCNTRL(c) isCNTRL_L1(c) isCNTRL_LC(c) 176 isdigit(c) isDIGIT(c) isDIGIT_L1(c) isDIGIT_LC(c) 177 isgraph(c) isGRAPH(c) isGRAPH_L1(c) isGRAPH_LC(c) 178 islower(c) isLOWER(c) isLOWER_L1(c) isLOWER_LC(c) 179 isprint(c) isPRINT(c) isPRINT_L1(c) isPRINT_LC(c) 180 ispunct(c) isPUNCT(c) isPUNCT_L1(c) isPUNCT_LC(c) 181 isspace(c) isSPACE(c) isSPACE_L1(c) isSPACE_LC(c) 182 isupper(c) isUPPER(c) isUPPER_L1(c) isUPPER_LC(c) 183 isxdigit(c) isXDIGIT(c) isXDIGIT_L1(c) isXDIGIT_LC(c) 184 185 tolower(c) toLOWER(c) toLOWER_L1(c) toLOWER_LC(c) 186 toupper(c) toUPPER(c) toUPPER_LC(c) 187 188To emphasize that you are operating only on ASCII characters, you can 189append C<_A> to each of the macros in the ASCII column: C<isALPHA_A>, 190C<isDIGIT_A>, and so on. 191 192(There is no entry in the Latin1 column for C<isascii> even though there 193is an C<isASCII_L1>, which is identical to C<isASCII>; the 194latter name is clearer. There is no entry in the Latin1 column for 195C<toupper> because the result can be non-Latin1. You have to use 196C<toUPPER_uni>, as described in L<perlapi/Character case changing>.) 197 198=head2 F<stdlib.h> functions 199 200 Instead Of: Use: 201 202 atof(s) Atof(s) 203 atol(s) Atol(s) 204 strtod(s, &p) Nothing. Just don't use it. 205 strtol(s, &p, n) Strtol(s, &p, n) 206 strtoul(s, &p, n) Strtoul(s, &p, n) 207 208Notice also the C<grok_bin>, C<grok_hex>, and C<grok_oct> functions in 209F<numeric.c> for converting strings representing numbers in the respective 210bases into C<NV>s. 211 212In theory C<Strtol> and C<Strtoul> may not be defined if the machine perl is 213built on doesn't actually have strtol and strtoul. But as those 2 214functions are part of the 1989 ANSI C spec we suspect you'll find them 215everywhere by now. 216 217 int rand() double Drand01() 218 srand(n) { seedDrand01((Rand_seed_t)n); 219 PL_srand_called = TRUE; } 220 221 exit(n) my_exit(n) 222 system(s) Don't. Look at pp_system or use my_popen 223 224 getenv(s) PerlEnv_getenv(s) 225 setenv(s, val) my_setenv(s, val) 226 227=head2 Miscellaneous functions 228 229You should not even B<want> to use F<setjmp.h> functions, but if you 230think you do, use the C<JMPENV> stack in F<scope.h> instead. 231 232For C<signal>/C<sigaction>, use C<rsignal(signo, handler)>. 233 234=head1 SEE ALSO 235 236L<perlapi>, L<perlapio>, L<perlguts> 237 238