C ++ convert hex string to signed integer

In C++, multiple methods can be used to convert hexadecimal strings to signed integers. Here are two common approaches, along with corresponding code examples.

Method 1: Using the Standard Library Function std::stoi

The std::stoi function in the C++ standard library converts strings to integers. It allows specifying the base of the string via the third parameter, enabling hexadecimal string parsing. Note that std::stoi by default produces signed integers.

Example Code:

cpp
#include <iostream>
#include <string>

int main() {
    std::string hexStr = "1A3F";
    int num = std::stoi(hexStr, 0, 16);
    
    std::cout << "Hexadecimal string " << hexStr << " converted to signed integer is " << num << std::endl;
    
    return 0;
}

Method 2: Using std::istringstream and std::hex

Another approach combines std::istringstream with the stream manipulator std::hex for conversion. This method also supports signed integer conversion.

Example Code:

cpp
#include <iostream>
#include <sstream>
#include <string>

int main() {
    std::string hexStr = "FF9B";
    std::istringstream converter(hexStr);
    int num;
    
    converter >> std::hex >> num;
    
    std::cout << "Hexadecimal string " << hexStr << " converted to signed integer is " << num << std::endl;
    
    return 0;
}

Key Considerations

1. Range Checking: While these methods effectively convert hexadecimal strings to integers, they do not perform range validation. If the hexadecimal value exceeds the int range, overflow may occur.
2. Error Handling: In practical applications, implement error handling mechanisms—such as checking for exceptions from std::stoi or verifying the state of std::istringstream—to ensure robust conversion.

These are two methods for converting hexadecimal strings to signed integers. When addressing programming challenges, selecting the appropriate method enhances code efficiency and stability.