将一串十六进制存储到char中？

Question

so I have a string that has a hex value in it. For example, my string may have

string a = "0x4D";

Would it be possible to assign 0x4D to a char ? Because I know that if I had

char c = 0x4D then I could print out its ASCII symbol, which would be M .

Is it possible to store "0x4D" into a char so that I can print out its ascii symbol? If anyone has any tips, that would be appreciated! If there's a better way to do this, please let me know! Thanks!

Answer 1

You can use strtol to convert the string to a number. You can then print this number or do other things you like with it.

Oh wait, you tagged it C++, and strtol is very much C-style. In C++, you can use a stringstream, and extract a number from it.

Answer 2

You can use std::stoi to convert the string to an integer (the base is auto-detected from the 0x prefix):

std::string str = "0x4D";
char c = static_cast<char>(std::stoi(str));
std::cout << c << std::endl;

However, this is not guaranteed to give you the ASCII character for that value. There are various translations between character sets that occur in this simple code alone. For example, the char s in the string literal "0x4D" are initialized with the corresponding value in the implementation-defined execution character set . The printed character is also up to interpretation by the medium that is displaying it.

The best you could do is provide a mapping from ASCII values to characters. You could do this with an array where the index is the ASCII value and the element is the corresponding character.

Answer 3

To use stringstreams as Bas suggests:

int x;
string s = "0x10";
stringstream ss;
ss << hex << s;
ss >> x;

But I think it's a wasteful way to do it.

Answer 4

Here is a solution based on std::stringstream :

std::istringstream iss ("0x4D");
iss.flags(std::ios::hex);
int i;
iss >> i;

std::cout << "[" << (char)i << "]" << std::endl;   //--> prints "[M]"