Conversion of wchar_t into char

Question

I am trying to convert wchar_t to char using wcstombs . And it works fine if only 1 value is converted but when more than 1 value is converted it gives unexpected results. These are two wchar_t values which I want to convert:

wchar_t szBuf[BUFF_LEN];
wchar_t szBuf1[BUFF_LEN];

and converting using wcstombs :

char user[]=""; 
int  length = wcstombs(user,szBuf,250);
char pass[]="";
int  length1 = wcstombs(pass,szBuf1,250);

say if I have alice in szBuf and alice123 in szBuf1 then pass will give the correct value but user will have a value like aalice123 . What is the error?

Answer 1

You're invoking Undefined Behaviour, because you're writing outside of the buffer bounds. Your user and pass buffers are each of length 1 (they're arrays initialised by a copy of "" ). So you're happily writing to random memory and anything could happen.

Answer 2

Your destination buffers are too small.

char user[] = ""; equals char user[1] = ""; . This means that you will write to unallocated space and it is undefined behaviour . This is very bad, because there are no guarantees what will happen.

Specify size for your destionation buffers: char user[250] = "";