I'm sure that is very simple problem but i'm only beginner in C++, so i'll be very thankful for any advice.

I have some functions that manadge passing variables from JS to C and back and need convert JavaScript string to C/C++ char * data type (path to a file).
There is the special function JS_ValueToString which gets JS value (js string) convert it and returns a pointer that points to a null-terminated string. So a past several days i'm trying apply JavaScript programming knowledge but with no success I've learned about pointers in C++ a little, but seems that this case differs from pointers to variables.

Below is the code i'm trying to finish:

Цитата

extern "C" { #include <TChar.h> #include "mm_jsapi.h" JSBool testFunc(JSContext *cx, JSObject *obj, unsigned int argc, jsval *argv, jsval *rval) { unsigned int leng; unsigned short p; char * my_str; p = *JS_ValueToString(cx, argv[0], &leng); my_str = ??? return JS_TRUE; } }

Just in case here is JS_ValueToString explanation from docs:

Цитата

unsigned short *JS_ValueToString() Usage unsigned short *JS_ValueToString(JSContext *cx, jsval v, unsigned int *pLength) Description This function extracts a function argument from a jsval structure, converts it to a string, if possible, and passes the converted value back to the caller. Note: Do not modify the returned buffer pointer or you might corrupt the data structures of the JavaScript interpreter. To change the string, you must copy the characters into another buffer and create a new JavaScript string. Arguments JSContext *cx, jsval v, unsigned int *pLength The cx argument is the opaque JSContext pointer that passes to the JavaScript function. The v argument is the jsval structure from which the string is to be extracted. The pLength argument is a pointer to an unsigned integer. This function sets *plength equal to the length of the string in bytes. Returns A pointer that points to a null-terminated string if successful or to a null value on failure. The calling routine must not free this string when it finishes.

THANK YOU FOR ANY ADVICE!

It looks strange that JS_ValueToString() function returns unsigned short* instead of char*. Are you sure that it doesn't return a unicode string?

In fact I've never worked with JS but I suppose this code should work correctly:

Цитата

extern "C" {      #include <TChar.h>      #include "mm_jsapi.h"      JSBool testFunc(JSContext *cx, JSObject *obj, unsigned int argc, jsval *argv, jsval *rval)      {           unsigned int leng;           char *my_str;           my_str = strdup((char*)JS_ValueToString(cx, argv[0], &leng));           // here goes your code           // and when "my_str" is no longer needed you must free the memory allocated by it           free(my_str);           return JS_TRUE;      } }

PS: Why don't you use Russian?

Это сообщение отредактировал(а) Дрон - 31.7.2004, 21:44