1PERLCLIB(1) Perl Programmers Reference Guide PERLCLIB(1)
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6 perlclib - Internal replacements for standard C library functions
7
9 One thing Perl porters should note is that perl doesn't tend to use
10 that much of the C standard library internally; you'll see very little
11 use of, for example, the ctype.h functions in there. This is because
12 Perl tends to reimplement or abstract standard library functions, so
13 that we know exactly how they're going to operate.
14 This is a reference card for people who are familiar with the C library
16 and who want to do things the Perl way; to tell them which functions
17 they ought to use instead of the more normal C functions.
18 Conventions
20 In the following tables:
22 "t"
24 is a type.
25 "p"
27 is a pointer.
28 "n"
30 is a number.
31 "s"
33 is a string.
34 "sv", "av", "hv", etc. represent variables of their respective types.
36 File Operations
38 Instead of the stdio.h functions, you should use the Perl abstraction
40 layer. Instead of "FILE*" types, you need to be handling "PerlIO*"
41 types. Don't forget that with the new PerlIO layered I/O abstraction
42 "FILE*" types may not even be available. See also the "perlapio" docu‐
43 mentation for more information about the following functions:
44 Instead Of: Use:
46 stdin PerlIO_stdin()
48 stdout PerlIO_stdout()
49 stderr PerlIO_stderr()
50 fopen(fn, mode) PerlIO_open(fn, mode)
52 freopen(fn, mode, stream) PerlIO_reopen(fn, mode, perlio) (Deprecated)
53 fflush(stream) PerlIO_flush(perlio)
54 fclose(stream) PerlIO_close(perlio)
55 File Input and Output
57 Instead Of: Use:
59 fprintf(stream, fmt, ...) PerlIO_printf(perlio, fmt, ...)
61 [f]getc(stream) PerlIO_getc(perlio)
63 [f]putc(stream, n) PerlIO_putc(perlio, n)
64 ungetc(n, stream) PerlIO_ungetc(perlio, n)
65 Note that the PerlIO equivalents of "fread" and "fwrite" are slightly
67 different from their C library counterparts:
68 fread(p, size, n, stream) PerlIO_read(perlio, buf, numbytes)
70 fwrite(p, size, n, stream) PerlIO_write(perlio, buf, numbytes)
71 fputs(s, stream) PerlIO_puts(perlio, s)
73 There is no equivalent to "fgets"; one should use "sv_gets" instead:
75 fgets(s, n, stream) sv_gets(sv, perlio, append)
77 File Positioning
79 Instead Of: Use:
81 feof(stream) PerlIO_eof(perlio)
83 fseek(stream, n, whence) PerlIO_seek(perlio, n, whence)
84 rewind(stream) PerlIO_rewind(perlio)
85 fgetpos(stream, p) PerlIO_getpos(perlio, sv)
87 fsetpos(stream, p) PerlIO_setpos(perlio, sv)
88 ferror(stream) PerlIO_error(perlio)
90 clearerr(stream) PerlIO_clearerr(perlio)
91 Memory Management and String Handling
93 Instead Of: Use:
95 t* p = malloc(n) Newx(id, p, n, t)
97 t* p = calloc(n, s) Newxz(id, p, n, t)
98 p = realloc(p, n) Renew(p, n, t)
99 memcpy(dst, src, n) Copy(src, dst, n, t)
100 memmove(dst, src, n) Move(src, dst, n, t)
101 memcpy/*(struct foo *) StructCopy(src, dst, t)
102 memset(dst, 0, n * sizeof(t)) Zero(dst, n, t)
103 memzero(dst, 0) Zero(dst, n, char)
104 free(p) Safefree(p)
105 strdup(p) savepv(p)
107 strndup(p, n) savepvn(p, n) (Hey, strndup doesn't exist!)
108 strstr(big, little) instr(big, little)
110 strcmp(s1, s2) strLE(s1, s2) / strEQ(s1, s2) / strGT(s1,s2)
111 strncmp(s1, s2, n) strnNE(s1, s2, n) / strnEQ(s1, s2, n)
112 Notice the different order of arguments to "Copy" and "Move" than used
114 in "memcpy" and "memmove".
115 Most of the time, though, you'll want to be dealing with SVs internally
117 instead of raw "char *" strings:
118 strlen(s) sv_len(sv)
120 strcpy(dt, src) sv_setpv(sv, s)
121 strncpy(dt, src, n) sv_setpvn(sv, s, n)
122 strcat(dt, src) sv_catpv(sv, s)
123 strncat(dt, src) sv_catpvn(sv, s)
124 sprintf(s, fmt, ...) sv_setpvf(sv, fmt, ...)
125 Note also the existence of "sv_catpvf" and "sv_vcatpvfn", combining
127 concatenation with formatting.
128 Sometimes instead of zeroing the allocated heap by using Newxz() you
130 should consider "poisoning" the data. This means writing a bit pattern
131 into it that should be illegal as pointers (and floating point num‐
132 bers), and also hopefully surprising enough as integers, so that any
133 code attempting to use the data without forethought will break sooner
134 rather than later. Poisoning can be done using the Poison() macro,
135 which has similar arguments as Zero():
136 Poison(dst, n, t)
138 Character Class Tests
140 There are two types of character class tests that Perl implements: one
142 type deals in "char"s and are thus not Unicode aware (and hence depre‐
143 cated unless you know you should use them) and the other type deal in
144 "UV"s and know about Unicode properties. In the following table, "c" is
145 a "char", and "u" is a Unicode codepoint.
146 Instead Of: Use: But better use:
148 isalnum(c) isALNUM(c) isALNUM_uni(u)
150 isalpha(c) isALPHA(c) isALPHA_uni(u)
151 iscntrl(c) isCNTRL(c) isCNTRL_uni(u)
152 isdigit(c) isDIGIT(c) isDIGIT_uni(u)
153 isgraph(c) isGRAPH(c) isGRAPH_uni(u)
154 islower(c) isLOWER(c) isLOWER_uni(u)
155 isprint(c) isPRINT(c) isPRINT_uni(u)
156 ispunct(c) isPUNCT(c) isPUNCT_uni(u)
157 isspace(c) isSPACE(c) isSPACE_uni(u)
158 isupper(c) isUPPER(c) isUPPER_uni(u)
159 isxdigit(c) isXDIGIT(c) isXDIGIT_uni(u)
160 tolower(c) toLOWER(c) toLOWER_uni(u)
162 toupper(c) toUPPER(c) toUPPER_uni(u)
163 stdlib.h functions
165 Instead Of: Use:
167 atof(s) Atof(s)
169 atol(s) Atol(s)
170 strtod(s, *p) Nothing. Just don't use it.
171 strtol(s, *p, n) Strtol(s, *p, n)
172 strtoul(s, *p, n) Strtoul(s, *p, n)
173 Notice also the "grok_bin", "grok_hex", and "grok_oct" functions in
175 numeric.c for converting strings representing numbers in the respective
176 bases into "NV"s.
177 In theory "Strtol" and "Strtoul" may not be defined if the machine perl
179 is built on doesn't actually have strtol and strtoul. But as those 2
180 functions are part of the 1989 ANSI C spec we suspect you'll find them
181 everywhere by now.
182 int rand() double Drand01()
184 srand(n) { seedDrand01((Rand_seed_t)n);
185 PL_srand_called = TRUE; }
186 exit(n) my_exit(n)
188 system(s) Don't. Look at pp_system or use my_popen
189 getenv(s) PerlEnv_getenv(s)
191 setenv(s, val) my_putenv(s, val)
192 Miscellaneous functions
194 You should not even want to use setjmp.h functions, but if you think
196 you do, use the "JMPENV" stack in scope.h instead.
197 For "signal"/"sigaction", use "rsignal(signo, handler)".
199
201 "perlapi", "perlapio", "perlguts"
202perl v5.8.8 2006-01-07 PERLCLIB(1)