chapter18ex1

// Osman Zakir
// 10 / 12 / 2017
// Bjarne Stroustrup: Programming: Principles and Practice Using C++ 2nd Edition
// Chapter 18 Exercise 1
// Exercise Specifications:
/**
 * Write a function, char* strdup(const char*), that copies a C-style string
 * into memory it allocates on the free store. Do not use any standard li-
 * brary functions. Do not use subscripting; use the dereference operator *
 * instead.
 */

#include "../../cust_std_lib_facilities.h"
#include <iostream>

char *strdup(const char *src);
int str_len(const char *str);
void str_cpy(char *dst, const char *src);

int main()
{
    char *str = const_cast<char*>("Osman Zakir");
    char *duplicate = strdup(str);
    for (int i = 0, n = str_len(duplicate); i < n; ++i)
    {
        std::cout << *(duplicate + i);
    }
    std::cout << '\n';
    keep_window_open();
}

char *strdup(const char *src)
{
    if (src == nullptr)
    {
        error("source string cannot be null");
    }
    char *dup = new char[str_len(src)];
    str_cpy(dup, src);
    return dup;
}

int str_len(const char *str)
{
    if (str == nullptr)
    {
        return -1;
    }
    int length = 0;
    for (int i = 0; *(str + i) != '\0'; ++i)
    {
        length++;
    }
    return length;
}

void str_cpy(char *dst, const char *src)
{
    for (int i = 0; *(src + i) != '\0'; ++i)
    {
        *(dst + i) = *(src + i);
    }
    int length = str_len(src);
    *(dst + length) = '\0';
}