replace apostrophes

Bjarne Stroustrup “Programming Principles and Practice Using C++”
Chapter 11 Exercise 7
Using std_lib_facilities.h by Bjarne Stroustrup.

[code language=”cpp”]
// Philipp Siedler
// Bjarne Stroustrup’s PPP
// Chapter 11 Exercise 7

#include "std_lib_facilities.h"

void replace_apostrophes(string& _w) {
if (_w == "can’t" || _w == "can’t ") {
_w = "cannot ";
}
if (_w == "won’t" || _w == "won’t ") {
_w = "will not ";
}
//in case word with apostrophe is in the end of the sentence
if (_w[_w.size() – 1] == ‘ ‘) {
if (_w[_w.size() – 2] == ‘t’ &&
_w[_w.size() – 3] == ‘\” &&
_w[_w.size() – 4] == ‘n’) {
string temp = "";
for (int i = 0; i < _w.size() – 4; i++) {
temp += _w[i];
}
_w = temp + " not ";
}
}
//in case word is in the beginning or in the middle of the sentence
else {
if (_w[_w.size() – 1] == ‘t’ &&
_w[_w.size() – 2] == ‘\” &&
_w[_w.size() – 3] == ‘n’) {
string temp = "";
for (int i = 0; i < _w.size() – 3; i++) {
temp += _w[i];
}
_w = temp + " not ";
}
}
}

void calculate() {
while (true) {
//init
cout << "enter a sentence" << endl;
char quit;
if (cin >> quit && quit == ‘x’) {
break;
}
cin.putback(quit);

//get chars and print them
char let;
vector<char> c_sentence;
vector<string> s_words;
while (cin.get(let)) {
if (let == ‘\n’) {
break;
}
else {
c_sentence.push_back(let);
}
}

//you entered
cout << "you entered: ";
for (char l : c_sentence) {
cout << l;
}
cout << "\n";

//transform char vector into strings
string temp;
for (int i = 0; i < c_sentence.size(); i++) {
if (!isspace(c_sentence[i])) {
temp += tolower(c_sentence[i]);
}
else {
if (i != c_sentence.size() – 1) {
temp += tolower(c_sentence[i]);
}
replace_apostrophes(temp);
s_words.push_back(temp);
temp = "";
}
if (i == c_sentence.size() – 1) {
replace_apostrophes(temp);
s_words.push_back(temp);
temp = "";
}
}

//output new sentence
for (string w : s_words) {
cout << w;
}
cout << "\n";
}
}

int main()
try
{
calculate();
keep_window_open();
}
catch (runtime_error e) {
cout << e.what() << endl;
keep_window_open();
}
catch (…) {
cout << "Exiting" << endl;
keep_window_open();
}
[/code]

Output:
enter a sentence
Can't stop, won't stop writing...
you entered: Can't stop, won't stop writing...
cannot stop, will not stop writing...
enter a sentence