c++ string to integer without stoi

To convert a string to an integer in C++ without using the stoi function, you can follow the following steps:

1. Include the necessary headers: To work with strings, you need to include the <string> header file. To work with streams, you need to include the <sstream> header file.

2. Declare the string: Declare a string variable that holds the string value you want to convert to an integer.

3. Create a stringstream object: Create a stringstream object, which allows you to read from and write to string-based streams.

4. Input the string: Use the stringstream object to input the string value into it. You can do this by using the << operator and passing the string variable as an argument.

5. Declare an integer variable: Declare an integer variable to store the converted integer value.

6. Output the integer: Use the >> operator on the stringstream object to extract the integer value and store it in the integer variable.

Here is an example code snippet that demonstrates the steps mentioned above:

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

int main() {
    std::string str = "1234";
    std::stringstream ss(str);
    int num;
    ss >> num;
    std::cout << "Converted integer: " << num << std::endl;
    return 0;
}

In this example, the string "1234" is converted to an integer using the steps outlined above. The converted integer value is then printed to the console.