数学之美上的正则表达式 匹配

#include <stdio.h>

/* match: search for regexp anywhere in text */
int match(char *regexp, char *text)
{
    if (regexp[0] == '^')
        return matchhere(regexp+1, text);
    do   /* must look even if string is empty */
    {
        if (matchhere(regexp, text))
            return 1;
    }
    while (*text++ != '');
    return 0;
}
/* matchhere: search for regexp at beginning of text */
int matchhere(char *regexp, char *text)
{
    if (regexp[0] == '')
        return 1;
    if (regexp[1] == '*')
        return matchstar(regexp[0], regexp+2, text);
    if (regexp[0] == '$' && regexp[1] == '')
        return *text == '';
    if (*text!='' && (regexp[0]=='.' || regexp[0]==*text))
        return matchhere(regexp+1, text+1);
    return 0;
}
/* matchstar: search for c*regexp at beginning of text */
int matchstar(int c, char *regexp, char *text)
{
    do   /* a * matches zero or more instances */
    {
        if (matchhere(regexp, text))
            return 1;
    }
    while (*text != '' && (*text++ == c || c == '.'));
    return 0;
}

int main()
{

}