I'm currently working on win32 application that uses sha1 hash on strings to generate keys for my map. I want to use the hash as DWORD
, so I can compute some calculations between hashes.
Since sha1 hash reproduces 160-bit hash values, I created a struct with 5 DWORD
(32-bit * 5 = 160).
struct _SHA1_HASH
{
DWORD dwFirst;
DWORD dwSecond;
DWORD dwThird;
DWORD dwFourth;
DWORD dwFifth;
}SHA1_HASH;
And I have hashed the string and stored into the struct.
void GenerateNodeKey()
{
// SHA-1 Hashing Process
// ex) strHash = 356A192B7913B04C54574D18C28D46E6395428AB
SHA1_HASH key;
string s_prefix = "0x";
key.dwFirst = strtol((s_prefix+strHash.substr(0,8)).c_str(), 0, 0); // first 8 bytes
...
...
key.dwFifth = strtol((s_prefix+strHash.substr(32,8)).c_str(), 0, 0); // last 8 bytes
}
But the problem arose when I try to print the value to check if they are alright.
wcout << hex
<< "Node ID : " << key.dwFirst << key.dwSecond << key.dwThird << key.dwFourth << key.dwFifth
<< dec
<< endl;
It prints out with no problems if the 8-byte hex value is less than 7FFFFFFF (2,147,483,647). However, when it is larger than the value, it just prints out the max number. I searched online to see if how large can DWORD
hold, and that was no problem (Related : What is the largest integer number base 16 that can be store in a variable of type dword?)
Can somebody help? Thanks in advance.
The strtol
function returns a signed long integer, which on windows has a range of -2,147,483,648 to 2,147,483,647.
If strtol
detects that the number generated is out of range, it will return the maximum long value. From cppreference:
If the converted value falls out of range of corresponding return type, a range error occurs (setting errno to ERANGE) and LONG_MAX, LONG_MIN, LLONG_MAX or LLONG_MIN is returned.
Use std::strtoul
instead.
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