Php extension development notes (6) ZVAL_STRING and ZVAL_STRINGL

: This article mainly introduces php extension development notes (6) ZVAL_STRING and ZVAL_STRINGL. if you are interested in PHP tutorials, refer to it. String Processing is a common operation. zend encapsulates many macros related to string operations. let's take a look at ZVAL_STRING and ZVAL_STRINGL.

#define ZVAL_STRING(z, s, duplicate) do {   \constchar *__s=(s);                \         zval *__z = (z);                    \         Z_STRLEN_P(__z) = strlen(__s);      \         Z_STRVAL_P(__z) = (duplicate?estrndup(__s, Z_STRLEN_P(__z)):(char*)__s);\         Z_TYPE_P(__z) = IS_STRING;          \     } while (0) #define ZVAL_STRINGL(z, s, l, duplicate) do {   \constchar *__s=(s); int __l=l;         \         zval *__z = (z);                        \         Z_STRLEN_P(__z) = __l;                  \         Z_STRVAL_P(__z) = (duplicate?estrndup(__s, __l):(char*)__s);\         Z_TYPE_P(__z) = IS_STRING;              \     } while (0)

Because many character string operations (such as substr) in php are finally performed on these macros, it is very important to understand these two macros here.

ZVAL_STRINGL does not need to use strlen to obtain the length of the string because the length parameter is given, which improves the performance.

I have mentioned this in the commonly used zend api. estrndup also encapsulates a layer. during php extension development, try to use system-encapsulated functions to optimize the memory, reduce memory leakage and other risks. There are several functions developed by e *. you can refer to the previous articles.

Estrndup definition

#define estrndup(s, length) _estrndup((s), (length) ZEND_FILE_LINE_CC ZEND_FILE_LINE_EMPTY_CC)

_ Estrndup definition

 ZEND_API char *_estrndup(constchar *s, uint length ZEND_FILE_LINE_DC ZEND_FILE_LINE_ORIG_DC) {     char *p; #ifdef ZEND_SIGNALS     TSRMLS_FETCH(); #endif     HANDLE_BLOCK_INTERRUPTIONS();     p = (char *) _emalloc(length+1 ZEND_FILE_LINE_RELAY_CC ZEND_FILE_LINE_ORIG_RELAY_CC);     if (UNEXPECTED(p == NULL)) {         HANDLE_UNBLOCK_INTERRUPTIONS();         return p;     }     memcpy(p, s, length);     p[length] = 0;     HANDLE_UNBLOCK_INTERRUPTIONS();     return p; }

You can search for related function definitions such as _ emalloc.

The above introduces the php extension development notes (6) ZVAL_STRING and ZVAL_STRINGL, including some content, and hope to help friends who are interested in PHP tutorials.