// CS1621 Fall 2005
// Strings in C++
#include <iostream>
#include <cstring>  // for old "c style" strings
#include <string>   // for string class
using namespace std;

const int MAX_S = 12;

int main()
{
    int i;
    char str1[MAX_S], str2[MAX_S];
    strcpy(str1, "0123456789");
    strcpy(str2, str1);  // copy one string to another
    cout << "str1: " << str1 << endl;
    cout << "str2: " << str2 << endl; 
    cout << "'" << str1 << "' has a length of " << strlen(str1) << endl;
    // Primitive strings in C++ have a special character, '\0' to mark
    // where they end, so that they can be more easily input and output
    // in a nicely formatted way.  Note that even though str1 is declared
    // to be a char array of length MAX_S (12), the length shown is only
    // 10, since the current "string" inside str1 has only 10 characters.

    if (strcmp(str1, str2) < 0)        // char arrays can be compared using
       cout << str1 << " < " << str2;  // the strcmp function. The idea
    else if (strcmp(str1, str2) == 0)  // of this is similar to the
                                       // compareTo method in the Java
       cout << str1 << " == " << str2; // Comparable interface
    else cout << str1 << " > " << str2;      
    cout << endl;                             

    char str3[4];          // One fundamental problem with the old c-style
    strcpy(str3, str1);    // strings is that they did not check array
    cout << "str3: " << str3 << endl;
                           // bounds during many of the operations.  For
                           // example, note that when printed out str3
            // contains the entire string that was in str1, even though the
            // size of str3 is only 5.  So where are the other characters
            // being stored?  The answer comes when we print out str2!
    cout << "str2: " << str2 << endl;
    cout << "The characters in str2's array are\n";
    for (i = 0; i < MAX_S; i++)
    {   
         if (str2[i] == '\0')
               cout << " ";
         else
               cout << str2[i];
    }
    cout << endl;
    // Now let's print out all of the strings, all from str3's point of
    // view.  Note that the access is going "backward" due to the way the
    // variables are stored on the run-time stack.
    cout << "The first " << 2 * MAX_S + 10 << " chars from str3 are\n";
    for (int i = 0; i < 2 * MAX_S + 10; i++)
    {   
         if (str3[i] == '\0')
               cout << " ";
         else
               cout << str3[i];
    }
    cout << endl;

    // The string class in C++ is somewhat safer than c strings, since
    // the methods restrict some access to the underlying data (which is
    // still basically an array of char).   However, as you can see below,
    // the lack of array bound enforcement could still lead to problems.
    string realstring(str1);  
    
    // c_str() method is for backward compatibility to c strings
    if (strcmp(realstring.c_str(), str1) == 0)             
        cout << realstring << " == " << str1 << endl;     
    // == is overloaded as well for compatibility
    if (realstring == str1)                             
         cout << realstring << " == " << str1 << endl;   

    string rs2 = realstring;
    rs2.insert(4,"wacky");
    cout << rs2 << endl;
    // Statement below throws an exception (out of bounds)
    // rs2.insert(25,"zany");

    // However, the index operator [] does not check, so we can still
    // violate the bounds of the string, as shown below.  However, now
    // the memory being accessed is in the heap rather than the run-time
    // stack.
    for (int i = 0; i < 60; i++)
    {
        cout << realstring[i] << ",";
        realstring[i] = 'x';   // uh oh, what am I changing?
    }
    cout << endl;
}