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1 | =head1 NAME |
2 | ||
3 | perlclib - Internal replacements for standard C library functions | |
4 | ||
5 | =head1 DESCRIPTION | |
6 | ||
7 | One thing Perl porters should note is that F<perl> doesn't tend to use that | |
8 | much of the C standard library internally; you'll see very little use of, | |
9 | for example, the F<ctype.h> functions in there. This is because Perl | |
10 | tends to reimplement or abstract standard library functions, so that we | |
11 | know exactly how they're going to operate. | |
12 | ||
13 | This is a reference card for people who are familiar with the C library | |
56d22bd2 | 14 | and who want to do things the Perl way; to tell them which functions |
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15 | they ought to use instead of the more normal C functions. |
16 | ||
17 | =head2 Conventions | |
18 | ||
19 | In the following tables: | |
20 | ||
21 | =over 3 | |
22 | ||
23 | =item C<t> | |
24 | ||
25 | is a type. | |
26 | ||
27 | =item C<p> | |
28 | ||
29 | is a pointer. | |
30 | ||
31 | =item C<n> | |
32 | ||
33 | is a number. | |
34 | ||
35 | =item C<s> | |
36 | ||
37 | is a string. | |
38 | ||
39 | =back | |
40 | ||
41 | C<sv>, C<av>, C<hv>, etc. represent variables of their respective types. | |
42 | ||
43 | =head2 File Operations | |
44 | ||
45 | Instead of the F<stdio.h> functions, you should use the Perl abstraction | |
46 | layer. Instead of C<FILE*> types, you need to be handling C<PerlIO*> | |
56d22bd2 | 47 | types. Don't forget that with the new PerlIO layered I/O abstraction |
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48 | C<FILE*> types may not even be available. See also the C<perlapio> |
49 | documentation for more information about the following functions: | |
50 | ||
51 | Instead Of: Use: | |
56d22bd2 | 52 | |
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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) (Deprecated) | |
59 | fflush(stream) PerlIO_flush(perlio) | |
60 | fclose(stream) PerlIO_close(perlio) | |
61 | ||
62 | =head2 File Input and Output | |
63 | ||
64 | Instead Of: Use: | |
65 | ||
66 | fprintf(stream, fmt, ...) PerlIO_printf(perlio, fmt, ...) | |
67 | ||
68 | [f]getc(stream) PerlIO_getc(perlio) | |
69 | [f]putc(stream, n) PerlIO_putc(perlio, n) | |
70 | ungetc(n, stream) PerlIO_ungetc(perlio, n) | |
71 | ||
72 | Note that the PerlIO equivalents of C<fread> and C<fwrite> are slightly | |
73 | different from their C library counterparts: | |
74 | ||
75 | fread(p, size, n, stream) PerlIO_read(perlio, buf, numbytes) | |
76 | fwrite(p, size, n, stream) PerlIO_write(perlio, buf, numbytes) | |
77 | ||
78 | fputs(s, stream) PerlIO_puts(perlio, s) | |
79 | ||
80 | There is no equivalent to C<fgets>; one should use C<sv_gets> instead: | |
81 | ||
82 | fgets(s, n, stream) sv_gets(sv, perlio, append) | |
83 | ||
84 | =head2 File Positioning | |
85 | ||
86 | Instead Of: Use: | |
87 | ||
88 | feof(stream) PerlIO_eof(perlio) | |
89 | fseek(stream, n, whence) PerlIO_seek(perlio, n, whence) | |
90 | rewind(stream) PerlIO_rewind(perlio) | |
91 | ||
92 | fgetpos(stream, p) PerlIO_getpos(perlio, sv) | |
93 | fsetpos(stream, p) PerlIO_setpos(perlio, sv) | |
94 | ||
95 | ferror(stream) PerlIO_error(perlio) | |
96 | clearerr(stream) PerlIO_clearerr(perlio) | |
97 | ||
98 | =head2 Memory Management and String Handling | |
99 | ||
702eb6d0 JH |
100 | Instead Of: Use: |
101 | ||
9f653bb5 SH |
102 | t* p = malloc(n) Newx(id, p, n, t) |
103 | t* p = calloc(n, s) Newxz(id, p, n, t) | |
702eb6d0 JH |
104 | p = realloc(p, n) Renew(p, n, t) |
105 | memcpy(dst, src, n) Copy(src, dst, n, t) | |
106 | memmove(dst, src, n) Move(src, dst, n, t) | |
4d567a56 | 107 | memcpy(dst, src, sizeof(t)) StructCopy(src, dst, t) |
702eb6d0 JH |
108 | memset(dst, 0, n * sizeof(t)) Zero(dst, n, t) |
109 | memzero(dst, 0) Zero(dst, n, char) | |
110 | free(p) Safefree(p) | |
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111 | |
112 | strdup(p) savepv(p) | |
113 | strndup(p, n) savepvn(p, n) (Hey, strndup doesn't exist!) | |
114 | ||
115 | strstr(big, little) instr(big, little) | |
116 | strcmp(s1, s2) strLE(s1, s2) / strEQ(s1, s2) / strGT(s1,s2) | |
117 | strncmp(s1, s2, n) strnNE(s1, s2, n) / strnEQ(s1, s2, n) | |
118 | ||
119 | Notice the different order of arguments to C<Copy> and C<Move> than used | |
120 | in C<memcpy> and C<memmove>. | |
121 | ||
122 | Most of the time, though, you'll want to be dealing with SVs internally | |
123 | instead of raw C<char *> strings: | |
124 | ||
125 | strlen(s) sv_len(sv) | |
126 | strcpy(dt, src) sv_setpv(sv, s) | |
127 | strncpy(dt, src, n) sv_setpvn(sv, s, n) | |
128 | strcat(dt, src) sv_catpv(sv, s) | |
129 | strncat(dt, src) sv_catpvn(sv, s) | |
130 | sprintf(s, fmt, ...) sv_setpvf(sv, fmt, ...) | |
131 | ||
328bf373 | 132 | Note also the existence of C<sv_catpvf> and C<sv_vcatpvfn>, combining |
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133 | concatenation with formatting. |
134 | ||
9f653bb5 | 135 | Sometimes instead of zeroing the allocated heap by using Newxz() you |
9965345d JH |
136 | should consider "poisoning" the data. This means writing a bit |
137 | pattern into it that should be illegal as pointers (and floating point | |
138 | numbers), and also hopefully surprising enough as integers, so that | |
139 | any code attempting to use the data without forethought will break | |
140 | sooner rather than later. Poisoning can be done using the Poison() | |
7e337ee0 | 141 | macros, which have similar arguments as Zero(): |
9965345d | 142 | |
7e337ee0 JH |
143 | PoisonWith(dst, n, t, b) scribble memory with byte b |
144 | PoisonNew(dst, n, t) equal to PoisonWith(dst, n, t, 0xAB) | |
145 | PoisonFree(dst, n, t) equal to PoisonWith(dst, n, t, 0xEF) | |
146 | Poison(dst, n, t) equal to PoisonFree(dst, n, t) | |
9965345d | 147 | |
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148 | =head2 Character Class Tests |
149 | ||
150 | There are two types of character class tests that Perl implements: one | |
151 | type deals in C<char>s and are thus B<not> Unicode aware (and hence | |
152 | deprecated unless you B<know> you should use them) and the other type | |
153 | deal in C<UV>s and know about Unicode properties. In the following | |
154 | table, C<c> is a C<char>, and C<u> is a Unicode codepoint. | |
155 | ||
156 | Instead Of: Use: But better use: | |
157 | ||
158 | isalnum(c) isALNUM(c) isALNUM_uni(u) | |
159 | isalpha(c) isALPHA(c) isALPHA_uni(u) | |
160 | iscntrl(c) isCNTRL(c) isCNTRL_uni(u) | |
161 | isdigit(c) isDIGIT(c) isDIGIT_uni(u) | |
162 | isgraph(c) isGRAPH(c) isGRAPH_uni(u) | |
163 | islower(c) isLOWER(c) isLOWER_uni(u) | |
164 | isprint(c) isPRINT(c) isPRINT_uni(u) | |
165 | ispunct(c) isPUNCT(c) isPUNCT_uni(u) | |
166 | isspace(c) isSPACE(c) isSPACE_uni(u) | |
167 | isupper(c) isUPPER(c) isUPPER_uni(u) | |
168 | isxdigit(c) isXDIGIT(c) isXDIGIT_uni(u) | |
169 | ||
170 | tolower(c) toLOWER(c) toLOWER_uni(u) | |
171 | toupper(c) toUPPER(c) toUPPER_uni(u) | |
172 | ||
173 | =head2 F<stdlib.h> functions | |
174 | ||
175 | Instead Of: Use: | |
176 | ||
177 | atof(s) Atof(s) | |
178 | atol(s) Atol(s) | |
4d567a56 VP |
179 | strtod(s, &p) Nothing. Just don't use it. |
180 | strtol(s, &p, n) Strtol(s, &p, n) | |
181 | strtoul(s, &p, n) Strtoul(s, &p, n) | |
f40a6c71 | 182 | |
53305cf1 | 183 | Notice also the C<grok_bin>, C<grok_hex>, and C<grok_oct> functions in |
2826e23d | 184 | F<numeric.c> for converting strings representing numbers in the respective |
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185 | bases into C<NV>s. |
186 | ||
187 | In theory C<Strtol> and C<Strtoul> may not be defined if the machine perl is | |
188 | built on doesn't actually have strtol and strtoul. But as those 2 | |
189 | functions are part of the 1989 ANSI C spec we suspect you'll find them | |
190 | everywhere by now. | |
191 | ||
192 | int rand() double Drand01() | |
193 | srand(n) { seedDrand01((Rand_seed_t)n); | |
194 | PL_srand_called = TRUE; } | |
56d22bd2 | 195 | |
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196 | exit(n) my_exit(n) |
197 | system(s) Don't. Look at pp_system or use my_popen | |
198 | ||
199 | getenv(s) PerlEnv_getenv(s) | |
200 | setenv(s, val) my_putenv(s, val) | |
201 | ||
202 | =head2 Miscellaneous functions | |
203 | ||
204 | You should not even B<want> to use F<setjmp.h> functions, but if you | |
205 | think you do, use the C<JMPENV> stack in F<scope.h> instead. | |
206 | ||
207 | For C<signal>/C<sigaction>, use C<rsignal(signo, handler)>. | |
208 | ||
209 | =head1 SEE ALSO | |
210 | ||
211 | C<perlapi>, C<perlapio>, C<perlguts> | |
212 |