Converting hex string to unsigned int issue C++ [closed]

Answer 1

int x = strtol(hex.c_str(), NULL, 16);

You can also use sscanf if you want to read a partial string. You mentioned you might want to just take the first two characters:

int x;
if( 1 == sscanf(hex.c_str(), "%2x", &x) ) {
    printf( "Value is: %d\n", x );
} else {
    printf( "Conversion failed\n" );
}

Note the above isn't really C++. You can use the std::hex stream modifier for that (note that I called your string mystr this time to avoid confusion (particularly if you've imported the namespace std):

int x;
std::istringstream iss(mystr);
bool ok = (iss >> std::hex >> x);

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[edit] I notice in your comment you ask about converting to an unsigned integer. In that case, why are you not explicitly declaring your integer as unsigned int?

For unsigned, you should use strtoul.