substrneg

substrneg.cpp

// substrneg.cpp
// juanfc 2024-11-11
// https://gist.github.com/juanfal/fe6f9f7369ff4358c80725781949a6ca

#include <iostream>
using namespace std;

int main()
{
    void tryThis(string s, int from, int end=-1);

    tryThis("abcdefgh",  2);
    tryThis("abcdefgh", -2);
    tryThis("abcdefgh", -1);
    tryThis("abcdefgh",  -3, -2);
    tryThis("abcdefgh",  4,  4);
    tryThis("abcdefgh",  4,  -2);
    tryThis("abcdefgh",  4,  3);
    tryThis("abcdefgh",  40,  50);

    return 0;
}

string substrneg(string s, int from, int end=-1)
{
    string r;
    int len = s.length();

    if (from < 0) from = len + from;
    if (end < 0)   end = len + end;
    if (end > len-1) end = len-1;

    for (int i = from; i <= end; ++i)
        r += s[i];

    return r;
}


void tryThis(string s, int from, int to)
{
    string substrneg(string s, int from, int end=-1);
    cout << "substrneg(\"" << s << "\", " << from <<", " << to << "): \"" << substrneg(s, from, to) << '"' << endl;
}