Замена подстроки

#include "iostream"
#include "algorithm"
#include "vector"
#include "fstream"
#include "string"
#include <sstream>
#include "omp.h"
using namespace std;
 
struct Abbreviation {
    string abb;
    string val;
};
void LowStr(string &x) {
    for (size_t i = 0; i < x.size(); ++i)
        x[i]=tolower(x[i]);
}
void RepAbb(string &x) {
    vector<Abbreviation> data;
    Abbreviation t1{ "can't","cannot" };
    Abbreviation t2{ "don't","do not" };
    data.push_back(t1);
    data.push_back(t2);
    for (size_t i = 0; i < data.size(); ++i) {
        int posf, pos = 0;
        while ((posf = x.find(data[i].abb,pos)) && x.npos != posf) {
            pos = posf+data[i].abb.size()+1;
            x.replace(posf, data[i].abb.size(), data[i].val);
        }
    }
}
void DeletePunct(string &x) {
    static const string signs = ".;,?'-";
    const char hyphen = '-';
    int posf,pos=0;
    while ((posf = x.find_first_of(signs, pos)) && x.npos != posf) {
        pos = posf + 1;
        if (x[posf] == hyphen && (posf > 0 && posf < x.size() - 1) && (isalnum(x[posf - 1]) && isalnum(x[posf + 1])))
            continue;
        x[posf] = 32;
    }
 
}
int main()
{
    string x;
    getline(cin, x);
    LowStr(x);
    RepAbb(x);
    DeletePunct(x);
    cout << x;
    system("pause");
    return 0;
}