如何用C语言编写一个合适的模式

how to write a appropriate pattern in pcre with C

本文关键字：一个 模式 何用 语言      更新时间：2023-10-16

现在我有一个字符串，它有许多子字符串，如"href="http://www.AAA.com"和其他字符，这里是我的问题，在我的C代码中我写:

char pattern[] = "/^href.*>$/g";

，我想取长字符串中的所有url。但这行不通。有人能帮帮我吗?感谢你的帮助。代码如下:

#define PCRE_STATIC //
#include <stdio.h>  
#include <string.h>  
#include <pcre.h>  
#define OVECCOUNT 30 /* should be a multiple of 3 */  
#define EBUFLEN 128  
#define BUFLEN 1024  
int main()  
{  
    pcre  *re;  
    const char *error;  
    int  erroffset;  
    int  ovector[OVECCOUNT];  
    int  rc, i;  
    char  src[] =  "<a href="http://union.elong.com/r/hotel/2000000000855850825" target="_blank">ss</a></td></tr><tr><td><a href="http://123.sogou.com/sub/fanyi.html" targedd</a></td><td><a href="http://123.sogou.com/sub/fantizi.html" target="_blank">繁 体 字</a></td><td><a href="http://123.sogou.com/sub/kuaidi.htm>快递查询</a></td></tr><tr><td><a href="http://q.stock.sohu.com/index.shtm>股票行情</a></td><td><a href="http://www.chinamobile.com/service/billservice/>话费查询</a></td><td><a href="http://auto.sohu.com/s2004/weizhangchaxun.shtml>交通违章</a></td></tr><tr><td>";
    char  pattern[] = "/^href.*>$/g";
    re = pcre_compile(pattern,
                      0,
                      &error,
                      &erroffset,
                      NULL);
    if (re == NULL) {
        printf("PCRE compilation failed at offset %d: %sn", erroffset, error);
        return 1;  
    }  
    rc = pcre_exec(re,
                   NULL,
                   src,
                   strlen(src),
                   0,
                   PCRE_MULTILINE,
                   ovector,
                   OVECCOUNT);
    if (rc < 0) {
        if (rc == PCRE_ERROR_NOMATCH) printf("Sorry, no match ...n");
        else printf("Matching error %dn", rc);
        pcre_free(re);  
        return 1;  
    }  
    printf("nOK, %d has matched ...nn",rc);
    for (i = 0; i < rc; i++) {
        char *substring_start = src + ovector[2*i];  
        int substring_length = ovector[2*i+1] - ovector[2*i];  
        printf("$%2d: %.*sn", i, substring_length, substring_start);
    }  
    pcre_free(re);
    return 0;  
}

试试这个正则表达式。

myregexp = pcre_compile("href\s*=\s*(['"])(.*?)\1", 0, &error, &erroroffset, NULL);
示例代码: 
pcre *myregexp;
const char *error;
int erroroffset;
int offsetcount;
int offsets[(2+1)*3]; // (max_capturing_groups+1)*3
myregexp = pcre_compile("href\s*=\s*(['"])(.*?)\1", 0, &error, &erroroffset, NULL);
if (myregexp != NULL) {
    offsetcount = pcre_exec(myregexp, NULL, subject, strlen(subject), 0, 0, offsets, (2+1)*3);
    while (offsetcount > 0) {
        // match offset = offsets[0];
        // match length = offsets[1] - offsets[0];
        if (pcre_get_substring(subject, &offsets, offsetcount, 0, &result) >= 0) {
            // Do something with match we just stored into result
        }
        offsetcount = pcre_exec(myregexp, NULL, subject, strlen(subject), 0, offsets[1], offsets, (2+1)*3);
    } 
} else {
    // Syntax error in the regular expression at erroroffset
}
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