Write a function that converts a string into an int. Assume the int is between 10 and 99. Do not use the atoi() or the stoi() function.

Written in C++

#include <iostream>

#include <sstream>

using namespace std;

int main()  {

   string num;

   cout<<"Enter a number: ";

   cin>>num;

   stringstream sstream(num);

   int convertnum = 0;

   sstream >> convertnum;

   cout << "Output: " << convertnum;

}

Explanation:

Without using atoi() or stoi(), we can make use of a string stream and this is explained as follows:

This line declares a string variable num

   string num;

This line prompts user for input

   cout<<"Enter a number: ";

This line gets user input

   cin>>num;

This line declares a string stream variable, sstream

   stringstream sstream(num);

This line declares and initializes the output variable, convertnum to 0

   int convertnum = 0;

The stream is passed into the output variable, convertnum

   sstream >> convertnum;

This line displays the output

   cout << "Output: " << convertnum;

Note that: if user enters a non integer character such as (alphabet, etc), only the integer part will be convert.

For instance,

40a will be outputted as 40