如何将字符串转换为无符号长整数。 曲折

Question

Hello I have a string parser who receives as its input a hex number: For Example: String X="0x120005f38"

As you can see the number is in HEX, how do I convert this to unsigned long?

If this was decimal based string I could use the string to unsigned long function. I am guessing there are a couple of steps, and I am not sure what order or functions to use. 1)Where I need to convert Hex into decimal 2)and String into unsigned long.

This seems very tricky to me, any ideas?

Answer 1

Use strtoul :

strtoul("0x120005f3", 0, 0);

strtoul reference on cplusplus.com . See how that works on Codepad .

EDIT: Changed to strtoul , did not notice that unsigned long is required.

Answer 2

您可以指定strtoul函数的base参数，该参数允许在字符串上使用0x前缀。

Answer 3

Using streams:

#include <iostream>
#include <sstream>
int main()
{
    const char* X="0x120005f38";
    std::stringstream ss(X);
    long long var;  //your value is too large for my long
    ss >> std::hex >> var;
    std::cout << var << ' ' << std::hex << var << '\n';
}

Answer 4

如果从字面上看这是您的代码，请不要使其成为带有0x前缀的文字整数： int x = 0x120005f38;