typedef struct _zend_string zend_string; zend_string是_zend_string的别名,_zend_string内容如下: struct _zend_string { zend_refcounted_h gc; zend_ulong h; /* hash value */ size_t len; char val[1]; }; zend_string定义了四个字段:gc, h, len, val[1],先看下gc的定义