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/* This is a demonstration program to illustrate the most straightforward ways |
/* This is a demonstration program to illustrate the most straightforward ways |
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of calling the PCRE regular expression library from a C program. See the |
of calling the PCRE regular expression library from a C program. See the |
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pcresample documentation for a short discussion. |
pcresample documentation for a short discussion ("man pcresample" if you have |
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the PCRE man pages installed). |
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Compile thuswise: |
In Unix-like environments, if PCRE is installed in your standard system |
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gcc -Wall pcredemo.c -I/opt/local/include -L/opt/local/lib \ |
libraries, you should be able to compile this program using this command: |
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-R/opt/local/lib -lpcre |
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Replace "/opt/local/include" and "/opt/local/lib" with wherever the include and |
gcc -Wall pcredemo.c -lpcre -o pcredemo |
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If PCRE is not installed in a standard place, it is likely to be installed with |
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support for the pkg-config mechanism. If you have pkg-config, you can compile |
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this program using this command: |
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gcc -Wall pcredemo.c `pkg-config --cflags --libs libpcre` -o pcredemo |
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If you do not have pkg-config, you may have to use this: |
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gcc -Wall pcredemo.c -I/usr/local/include -L/usr/local/lib \ |
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-R/usr/local/lib -lpcre -o pcredemo |
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Replace "/usr/local/include" and "/usr/local/lib" with wherever the include and |
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library files for PCRE are installed on your system. Only some operating |
library files for PCRE are installed on your system. Only some operating |
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systems (e.g. Solaris) use the -R option. |
systems (e.g. Solaris) use the -R option. |
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*/ |
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Building under Windows: |
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If you want to statically link this program against a non-dll .a file, you must |
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define PCRE_STATIC before including pcre.h, otherwise the pcre_malloc() and |
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pcre_free() exported functions will be declared __declspec(dllimport), with |
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unwanted results. So in this environment, uncomment the following line. */ |
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/* #define PCRE_STATIC */ |
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#include <stdio.h> |
#include <stdio.h> |
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#include <string.h> |
#include <string.h> |
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int rc, i; |
int rc, i; |
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/************************************************************************* |
/************************************************************************** |
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* First, sort out the command line. There is only one possible option at * |
* First, sort out the command line. There is only one possible option at * |
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* the moment, "-g" to request repeated matching to find all occurrences, * |
* the moment, "-g" to request repeated matching to find all occurrences, * |
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* like Perl's /g option. We set the variable find_all non-zero if it is * |
* like Perl's /g option. We set the variable find_all to a non-zero value * |
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* present. Apart from that, there must be exactly two arguments. * |
* if the -g option is present. Apart from that, there must be exactly two * |
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*************************************************************************/ |
* arguments. * |
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**************************************************************************/ |
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find_all = 0; |
find_all = 0; |
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for (i = 1; i < argc; i++) |
for (i = 1; i < argc; i++) |
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/************************************************************************* |
/************************************************************************* |
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* If the compilation succeeded, we call PCRE again, in order to do a * |
* If the compilation succeeded, we call PCRE again, in order to do a * |
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* pattern match against the subject string. This just does ONE match. If * |
* pattern match against the subject string. This does just ONE match. If * |
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* further matching is needed, it will be done below. * |
* further matching is needed, it will be done below. * |
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*************************************************************************/ |
*************************************************************************/ |
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*/ |
*/ |
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default: printf("Matching error %d\n", rc); break; |
default: printf("Matching error %d\n", rc); break; |
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} |
} |
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pcre_free(re); /* Release memory used for the compiled pattern */ |
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return 1; |
return 1; |
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} |
} |
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/************************************************************************* |
/************************************************************************* |
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* We have found the first match within the subject string. If the output * |
* We have found the first match within the subject string. If the output * |
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* vector wasn't big enough, set its size to the maximum. Then output any * |
* vector wasn't big enough, say so. Then output any substrings that were * |
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* substrings that were captured. * |
* captured. * |
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*************************************************************************/ |
*************************************************************************/ |
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/* The output vector wasn't big enough */ |
/* The output vector wasn't big enough */ |
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} |
} |
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/************************************************************************* |
/************************************************************************** |
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* That concludes the basic part of this demonstration program. We have * |
* That concludes the basic part of this demonstration program. We have * |
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* compiled a pattern, and performed a single match. The code that follows* |
* compiled a pattern, and performed a single match. The code that follows * |
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* first shows how to access named substrings, and then how to code for * |
* shows first how to access named substrings, and then how to code for * |
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* repeated matches on the same subject. * |
* repeated matches on the same subject. * |
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*************************************************************************/ |
**************************************************************************/ |
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/* See if there are any named substrings, and if so, show them by name. First |
/* See if there are any named substrings, and if so, show them by name. First |
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we have to extract the count of named parentheses from the pattern. */ |
we have to extract the count of named parentheses from the pattern. */ |
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* * |
* * |
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* If the previous match WAS for an empty string, we can't do that, as it * |
* If the previous match WAS for an empty string, we can't do that, as it * |
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* would lead to an infinite loop. Instead, a special call of pcre_exec() * |
* would lead to an infinite loop. Instead, a special call of pcre_exec() * |
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* is made with the PCRE_NOTEMPTY and PCRE_ANCHORED flags set. The first * |
* is made with the PCRE_NOTEMPTY_ATSTART and PCRE_ANCHORED flags set. * |
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* of these tells PCRE that an empty string is not a valid match; other * |
* The first of these tells PCRE that an empty string at the start of the * |
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* possibilities must be tried. The second flag restricts PCRE to one * |
* subject is not a valid match; other possibilities must be tried. The * |
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* match attempt at the initial string position. If this match succeeds, * |
* second flag restricts PCRE to one match attempt at the initial string * |
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* an alternative to the empty string match has been found, and we can * |
* position. If this match succeeds, an alternative to the empty string * |
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* proceed round the loop. * |
* match has been found, and we can proceed round the loop. * |
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*************************************************************************/ |
*************************************************************************/ |
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if (!find_all) return 0; /* Finish unless -g was given */ |
if (!find_all) |
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{ |
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pcre_free(re); /* Release the memory used for the compiled pattern */ |
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return 0; /* Finish unless -g was given */ |
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} |
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/* Loop for second and subsequent matches */ |
/* Loop for second and subsequent matches */ |
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if (ovector[0] == ovector[1]) |
if (ovector[0] == ovector[1]) |
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{ |
{ |
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if (ovector[0] == subject_length) break; |
if (ovector[0] == subject_length) break; |
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options = PCRE_NOTEMPTY | PCRE_ANCHORED; |
options = PCRE_NOTEMPTY_ATSTART | PCRE_ANCHORED; |
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} |
} |
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/* Run the next matching operation */ |
/* Run the next matching operation */ |
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if (rc < 0) |
if (rc < 0) |
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{ |
{ |
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printf("Matching error %d\n", rc); |
printf("Matching error %d\n", rc); |
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pcre_free(re); /* Release memory used for the compiled pattern */ |
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return 1; |
return 1; |
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} |
} |
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} /* End of loop to find second and subsequent matches */ |
} /* End of loop to find second and subsequent matches */ |
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printf("\n"); |
printf("\n"); |
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pcre_free(re); /* Release memory used for the compiled pattern */ |
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return 0; |
return 0; |
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} |
} |
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