How to use stoi function In C++
stoi is a function in the string header file. The function takes as an argument a string and returns the converted integer. The function syntax is as follows:
Syntax:
int stoi (char *str, size_t* idx, int base);
Here,
str: The input string that is to be converted
size: Pointer to the object whose value is set by the function
base: It specifies the radix to determine the value type of input string
Since the requirement is to convert the Hex string to an Integer, the base would be 16.
Example:
C++
// C++ program to implement// stoi() function to convert// hex string to signed integer#include <iostream>#include <string>using namespace std;// Driver codeint main(){ // The Hex string that is to // be converted char *str = "4AF1"; // Calling the function stoi // Storing the return value in // an unsigned integer signed number = stoi(str, 0, 16); // Displaying the unsigned integer // equivalent to the hex cout << "hex: " << str << "\tinteger: " << number; return 0;} |
hex: 4AF1 integer: 19185
Explanation: Firstly, the relevant header files were included. Then a string is defined containing the hex 4AF1 as value. This string (character array) is passed to the stoi function along with 0 and 16 as arguments. Where 0 is the default value of the size, and 16 is for hexadecimal conversion. The return value of the function is stored in a signed integer. This Hex string, along with its signed integer equivalent, is later displayed.
Convert Hex String to Signed Integer in C++
This article discusses converting a hex string to a signed integer in C++. There are 5 ways to do this in C++:
- Using stoi() function.
- Using stoul() function.
- Using sscanf() function.
- Using stringstream method.
- Using boost:lexical_cast.