Converting CString to unsigned long

Question

I am trying to convert a string to unsigned long. Here is the code

lCardNum = wcstoul(sCardNo.GetBuffer(sCardNo.GetLength()), NULL,0);

My sCardNo(CString) value is 4294967359. Why do I get lCardNum(unsigned long) as 4294967295 ?

Answer 1

Assuming that your unsigned long integer is 32-bits wide, then you are overflowing it. 0xFFFFFFFF is 4294967295. Your wanted 4294967359 is 0x10000003F, ie , it needs 33 bits.

Go for unsigned long long or __int64 on a Windows box, lookup _wcstoui64 .