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SunOS man pages : regex (1)

Standard C Library Functions                           regcmp(3C)


regcmp, regex - compile and execute regular expression


#include <libgen.h> char *regcmp(const char *string1, /* char *string2 */ ..., int /*(char*)0*/); char *regex(const char *re, const char *subject, /* char *ret0 */ ...); extern char *__loc1;


The regcmp() function compiles a regular expression (con- sisting of the concatenated arguments) and returns a pointer to the compiled form. The malloc(3C) function is used to create space for the compiled form. It is the user's respon- sibility to free unneeded space so allocated. A NULL return from regcmp() indicates an incorrect argument. regcmp(1) has been written to generally preclude the need for this routine at execution time. The regex() function executes a compiled pattern against the subject string. Additional arguments are passed to receive values back. The regex() function returns NULL on failure or a pointer to the next unmatched character on success. A global character pointer __loc1 points to where the match began. The regcmp() and regex() functions were mostly bor- rowed from the editor ed(1); however, the syntax and seman- tics have been changed slightly. The following are the valid symbols and associated meanings. []*.^ This group of symbols retains its meaning as described on the regexp(5) manual page. $ Matches the end of the string; \n matches a newline. - Within brackets the minus means through. For example, [a-z] is equivalent to []. The - can appear as itself only if used as the first or last character. For example, the character class expression []-] matches the characters ] and -. + A regular expression followed by + means one or more times. For example, [0-9]+ is equivalent to [0-9][0-9]*. {m} {m,} {m,u} Integer values enclosed in {} indicate the number of times the preceding regular expression is to be applied. The value m is the minimum number and u is a SunOS 5.8 Last change: 29 Dec 1996 1 Standard C Library Functions regcmp(3C) number, less than 256, which is the maximum. If only m is present (that is, {m}), it indicates the exact number of times the regular expression is to be applied. The value {m,} is analogous to {m,infinity}. The plus ( +) and star (*) operations are equivalent to {1,} and {0,} respectively. ( ... )$n The value of the enclosed regular expression is to be returned. The value will be stored in the (n+1)th argument following the subject argument. At most, ten enclosed regular expressions are allowed. The regex() function makes its assignments unconditionally. ( ... ) Parentheses are used for grouping. An operator, for example, *, +, {}, can work on a single character or a regular expression enclosed in parentheses. For exam- ple, (a*(cb+)*)$0. By necessity, all the above defined symbols are special. They must, therefore, be escaped with a \ (backslash) to be used as themselves.


Example 1: Example matching a leading newline in the subject string. The following example matches a leading newline in the sub- ject string pointed at by cursor. char *cursor, *newcursor, *ptr; ... newcursor = regex((ptr = regcmp("^\n", (char *)0)), cursor); free(ptr); The following example matches through the string Testing3 and returns the address of the character after the last matched character (the ``4''). The string Testing3 is copied to the character array ret0. char ret0[9]; char *newcursor, *name; ... name = regcmp("([A-Za-z][A-za-z0-9]{0,7})$0", (char *)0); newcursor = regex(name, "012Testing345", ret0); The following example applies a precompiled regular expres- sion in file.i (see regcmp(1)) against string. #include "file.i" char *string, *newcursor; ... newcursor = regex(name, string); SunOS 5.8 Last change: 29 Dec 1996 2 Standard C Library Functions regcmp(3C)




See attributes(5) for descriptions of the following attri- butes: ____________________________________________________________ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | |_____________________________|_____________________________| | MT-Level | MT-Safe | |_____________________________|_____________________________|


ed(1), regcmp(1), malloc(3C), attributes(5), regexp(5)


The user program may run out of memory if regcmp() is called iteratively without freeing the vectors no longer required. When compiling multithreaded applications, the _REENTRANT flag must be defined on the compile line. This flag should only be used in multithreaded applications. SunOS 5.8 Last change: 29 Dec 1996 3