1_fix_string

#include <iostream>
#include <stdlib.h>
#include <string.h>
using namespace std;

string inputString();
int inputForceInteger(string);
char* copyStrs(string, char *);
char* subStrs(char*,char *);
char* getStrs(int,int,char *,char *);

int main()
{
    char *strs;
    char *sub;

    string s1 = inputString();
    strs = copyStrs(s1, strs);
    sub = subStrs(strs,sub);
    std::cout << "sub string: [" << sub << "]" << endl;

    return 0;
}

string inputString()
{
    cout << "Type a string: ";
    string s;

    getline(cin,s, '\n');
    return s;
}

char* copyStrs(string s, char *strs)
{
    strs = (char*) malloc(s.length() + 1 * sizeof(char));

    int i = 0;
    for (i = 0; i < s.length(); i++) strs[i] = s.at(i);

    strs[i] ='\0';
    return strs;
}

char* subStrs(char* strs, char* newStrs)
{
    int start;
    int end;

    // 2 - error when input # integer type
    start = inputForceInteger("Start point (Integer value): ");
    end = inputForceInteger("End point (Integer value): ");

    newStrs = getStrs(start,end,strs,newStrs);
    return newStrs;
}

int inputForceInteger(string cmt)
{
    string s;
    do
    {
        cout << cmt;
        getline(cin,s, '\n');

    } while(atol(s.c_str()) == 0 && !(s.length() == 1 && s[0] == '0'));

    return atoi(s.c_str());
}

char* getStrs(int start,int end,char* strs,char* newStrs)
{
    if(end > strlen(strs))
    {
        cout << "End value too large" << endl;
        return "\0";
    }

    int len = end - start + 1;
    newStrs = (char*) calloc (len, sizeof(char));

    int i = 0;
    for (i=0; i < len - 1; i++) newStrs[i] = strs[start + i];
    newStrs[i] = '\0';

    return newStrs;
}