来看一个php函数的源码。 strpos 在字符串中找到指定字符串第一次出现的位置。
PHP_FUNCTION(strpos)
{
zval *needle;
char *haystack;
char *found = NULL;
char needle_char[2];
long offset = 0;
int haystack_len;
if (zend_parse_parameters(ZEND_NUM_ARGS() TSRMLS_CC, "sz|l", &haystack, &haystack_len, &needle, &offset) == FAILURE) {
return;
}
if (offset < 0 || offset > haystack_len) {
php_error_docref(NULL TSRMLS_CC, E_WARNING, "Offset not contained in string");
RETURN_FALSE;
}
if (Z_TYPE_P(needle) == IS_STRING) {
if (!Z_STRLEN_P(needle)) {
php_error_docref(NULL TSRMLS_CC, E_WARNING, "Empty needle");
RETURN_FALSE;
}
found = php_memnstr(haystack + offset,
Z_STRVAL_P(needle),
Z_STRLEN_P(needle),
haystack + haystack_len);
} else {
if (php_needle_char(needle, needle_char TSRMLS_CC) != SUCCESS) {
RETURN_FALSE;
}
needle_char[1] = 0;
found = php_memnstr(haystack + offset,
needle_char,
1,
haystack + haystack_len);
}
if (found) {
RETURN_LONG(found - haystack);
} else {
RETURN_FALSE;
}
}
