C++ convert hex string to signed integer

Question

I want to convert a hex string to a 32 bit signed integer in C++.

So, for example, I have the hex string \"fffefffe\". The binary representation of this is 111111

Answer 1

This worked for me:

string string_test = "80123456";
unsigned long x;
signed long val;

std::stringstream ss;
ss << std::hex << string_test;
ss >> x;
// ss >> val;  // if I try this val = 0
val = (signed long)x;  // However, if I cast the unsigned result I get val = 0x80123456