c++ - Windows malloc issue? -

in windows (visual studio c++ 2010) i'm trying simple string copy. here's code:

char * filename; (...) filename = (char *) malloc(wcslen(argv[(i + 1)]) + 1); wcscpy((wchar_t *)filename, argv[i + 1]); wprintf(l"filename is: %s", filename); 

and program crashes if argv[i + 1] if bigger 14. if 14 or less runs fine. see bellow.

c:\visual studio 2010\projects\test\release>test.exe -f 12345678901234 aa asas asas first argument  argv[1]   -f argc = 6 filename is: 12345678901234 

what's gotcha here? missing? thanks.

realise wcslen() returns number of wide characters in string, not number of bytes occupies. , malloc() requires number of bytes...

so need multiply number of wide characters size of wide character before passing malloc():

filename = (char *) malloc( (wcslen(argv[(i + 1)]) + 1) * sizeof(wchar_t));

but then, you're typecasting (char *). if argv declared char *argv[] or char **argv, wcslen() wrong function use anyway: need strlen().