This piece of code converts string text to integer.

string_to_text.cpp

#include <iostream>
#include <stdexcept>
#include <cmath>
using namespace std;

/**
 * Reports any non numeric charaters in a string. Removes if just whitespace.
 * @param {string} str - String to convert.
 * @return {string} String with just numbers.
 */
string just_nums(string str)
{
	string no_spaces = "";
	for (int i = 0; i < str.length(); ++i)
	{
		int dig = str.at(i)-48;

		// If a space.
		if ( dig == -16 ) 
		{}
		// 0 - 9
		else if (dig > -1 && dig < 10)
			no_spaces += str.at(i);
		// non numeric
		else
			throw logic_error("There was a non character");
	}

	return no_spaces;
}

/**
 * Converts a legit number in string form to integer.
 * @param {string} num - Number to convert to int.
 * @return {int} Integer form of string.
 */
int str_to_int(string num)
{
	const int LEN = num.length();
	int tot = 0;

	for (int i = 0; i < LEN; ++i)
		tot += (num.at(i)-48) * pow(10,LEN-i-1);

	return tot;
}

int main()
{
	try
	{
		// just nums first
		string nummed = just_nums("234  ");
		// Convert to number
		cout << str_to_int(nummed) << endl;
	}	
	catch (logic_error err)
	{
		cerr << err.what() << endl;
	}
	return 0;
}