PHP的json_encode使用分析说明_PHP教程

{a : 'abc'} {'a' : 'abc'} {a : "abc"} {"a" : "abc"}

$ret_json='{"%s":"%s"}';

echo json_encode($ret_json,"a","abc");

PHP_JSON_API void php_json_encode(smart_str *buf, zval *val, int options TSRMLS_DC) /* {{{ */
{
switch (Z_TYPE_P(val))
{
case IS_NULL:
smart_str_appendl(buf, "null", 4); //输出NULL
break;

case IS_BOOL:
if (Z_BVAL_P(val)) {
smart_str_appendl(buf, "true", 4);//输出true
} else {
smart_str_appendl(buf, "false", 5);//输出false
}
break;

case IS_LONG:
smart_str_append_long(buf, Z_LVAL_P(val));//输出长整形的值
break;

case IS_DOUBLE:
{
char *d = NULL;
int len;
double dbl = Z_DVAL_P(val);

if (!zend_isinf(dbl) && !zend_isnan(dbl)) {//非无穷尽
len = spprintf(&d, 0, "%.*k", (int) EG(precision), dbl);
smart_str_appendl(buf, d, len);
efree(d);
} else {
php_error_docref(NULL TSRMLS_CC, E_WARNING, "double %.9g does not conform to the JSON spec, encoded as 0", dbl);
smart_str_appendc(buf, '0');
}
}
break;

case IS_STRING://字符串
json_escape_string(buf, Z_STRVAL_P(val), Z_STRLEN_P(val), options TSRMLS_CC);
break;

case IS_ARRAY://数组和对象
case IS_OBJECT:
json_encode_array(buf, &val, options TSRMLS_CC);
break;

default:
php_error_docref(NULL TSRMLS_CC, E_WARNING, "type is unsupported, encoded as null");
smart_str_appendl(buf, "null", 4);
break;
}

return;
}