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strpos

mixed strpos ( string $haystack, mixed $needle [, int $offset = 0 ] )
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    $str = "hello";
    $pos = strpos($str, 111);
    // 111µÄASCIIÖµÊÇo£¬Òo´Ë$pos = 4
    strposºËÐÄÔ´Âe

    if (Z_TYPE_P(needle) == IS_STRING) {
       if (!Z_STRLEN_P(needle)) {
         php_error_docref(NULL TSRMLS_CC, E_WARNING, "Empty needle");
         RETURN_FALSE;
       }

       // µ÷ÓÃphp_memnstrº¯Êý²eÕÒneedle
       found = php_memnstr(haystack + offset,
                  Z_STRVAL_P(needle),
                  Z_STRLEN_P(needle),
                  haystack + haystack_len);
       } else {
         // Èç¹u²»ÊÇ×Ö*u´®£¬×ª»»³ÉÊý×Ö²¢¸³ÖµÎª¸ÃÊý×ÖµÄASCII×Ö*u¡£
         if (php_needle_char(needle, needle_char TSRMLS_CC) != SUCCESS) {
            RETURN_FALSE;
         }
         //ÉeÖýaÊø×Ö*u
         needle_char[1] = 0;
         found = php_memnstr(haystack + offset,
                  needle_char,
                  1,
                  haystack + haystack_len);
    ¡¡¡¡ }
    }

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define php_memnstr zend_memnstr

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    static inline char *
    zend_memnstr(char *haystack, char *needle, int needle_len, char *end)
    {
      char *p = haystack;
      char ne = needle[needle_len-1];
      if (needle_len == 1) {
        return (char *)memchr(p, *needle, (end-p));
      }

      if (needle_len > end-haystack) {
        return NULL;
      }

      // µÚÒ»¸oÓÅ»¯£¬Ö»²eÕÒend - needle_len´Î
      end -= needle_len;

      while (p <= end) {
        // µÚ¶þ¸oÓÅ»¯£¬ÏÈÅжÏ×Ö*u´®µÄ¿ªÍ*ºÍ½aβÊÇ*ñÒ»ÑuÔÙÅжÏÕu¸o×Ö*u´®
        if ((p = (char *)memchr(p, *needle, (end-p+1))) && ne == p[needle_len-1]) {
          if (!memcmp(needle, p, needle_len-1)) {
            return p;
          }
        }

        if (p == NULL) {
          return NULL;
        }

        p++;
      }

      return NULL;
    }

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strstr

string strstr ( string $haystack, mixed $needle [, bool $before_needle = false ] )

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Õa¸oº¯ÊýµÄÇø*Ö´oСдµÄ¡£

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strstrºËÐÄÔ´Âe

    if (found) {
        // ¼ÆËa³ofoundµÄλÖÃ
        found_offset = found - haystack;
        if (part) {
          RETURN_STRINGL(haystack, found_offset, 1);
        } else {
          RETURN_STRINGL(found, haystack_len - found_offset, 1);
        }
    }

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stripos

mixed stripos ( string $haystack, string $needle [, int $offset = 0 ] )

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stristr

string stristr ( string $haystack, mixed $needle [, bool $before_needle = false ] ) ²»Çø*Ö´oСдµÄstrstr¡£

ºËÐÄÔ´Âe

    // ¿½±´Ò»*Ýhaystack
    haystack_dup = estrndup(haystack, haystack_len);

    if (Z_TYPE_P(needle) == IS_STRING) {
      char *orig_needle;
      if (!Z_STRLEN_P(needle)) {
        php_error_docref(NULL TSRMLS_CC, E_WARNING, "Empty needle");
        efree(haystack_dup);
        RETURN_FALSE;
      }
      orig_needle = estrndup(Z_STRVAL_P(needle), Z_STRLEN_P(needle));
      // µ÷ÓÃphp_stristrº¯ÊýÕÒ³oorig_needleµÄÖµ¡£
      found = php_stristr(haystack_dup, orig_needle,  haystack_len, Z_STRLEN_P(needle));
      efree(orig_needle);
    } else {
      if (php_needle_char(needle, needle_char TSRMLS_CC) != SUCCESS) {
        efree(haystack_dup);
        RETURN_FALSE;
      }
      needle_char[1] = 0;

      found = php_stristr(haystack_dup, needle_char,  haystack_len, 1);
    }

    if (found) {
      found_offset = found - haystack_dup;
      if (part) {
        RETVAL_STRINGL(haystack, found_offset, 1);
      } else {
        RETVAL_STRINGL(haystack + found_offset, haystack_len - found_offset, 1);
      }
    } else {
      RETVAL_FALSE;
    }

    // ÊÍ*űaÁ¿
    efree(haystack_dup);

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    PHPAPI char *php_stristr(char *s, char *t, size_t s_len, size_t t_len)
    {
      php_strtolower(s, s_len);
      php_strtolower(t, t_len);
      return php_memnstr(s, t, t_len, s + s_len);
    } 

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