// Program to perform various string operations.
// Assignment-08
// stroper.cpp, Author - Krishna Kumar Khatri.

// Uncomment ONLY the following line if you are using Turbo/Borland compiler.
// #define TC
#ifdef TC
	#include <iostream.h>
#else
	#include <iostream>
	using namespace std;
#endif
#include <conio.h>  // For getch.
const int MAXLEN = 31;

int len(const char str[])
{
    int ln;
    for (ln = 0; str[ln] != '\0'; ln++)
        ;
    return ln;
}

char* copy(char strd[], const char strs[])
{
    int ln = len(strs);
    int i;
    
    for (i = 0; i < ln; i++)
        strd[i] = strs[i];
    strd[i] = '\0';

    return strd;
}

char* concat(const char strf[], const char strs[])
{
    int ln1 = len(strf);
    int ln2 = len(strs);
    char* res = new char[2 * MAXLEN];
    int i, j, flag = 0;
    
    for (i = 0, j = 0; i < ln1 + ln2; i++, j++) {
        if (strf[j] == '\0') {
            flag = 1;
            j = 0;
        }
        flag == 0 ? res[i] = strf[j] : res[i] = strs[j];
    }
    res[i] = '\0';

    return res;
}

char* ucase(const char str[])
{
    char* res = new char[MAXLEN];
    int ln = len(str);
    int i;
    
    for (i = 0; i < ln; i++)
        str[i] >= 97 && str[i] <= 122 ? 
               res[i] = str[i] - 32 :
               res[i] = str[i];
    res[i] = '\0';
    
    return res;
}

char* lcase(const char str[])
{
    char* res = new char[MAXLEN];
    int ln = len(str);
    int i;
    
    for (i = 0; i < ln; i++)
        str[i] >= 65 && str[i] <= 90 ? 
               res[i] = str[i] + 32 :
               res[i] = str[i];
    res[i] = '\0';
    
    return res;
}

short compare(const char str1[], const char str2[])
{
    int ln = len(str1) < len(str2) ?
             len(str1) : len(str2);
    int i;
    
    for (i = 0; i < ln; i++)
        if (str1[i] != str2[i])
            return str1[i] < str2[i++] ? -1 : 1;
    return 0;
}

void breakup(const char str[], int pos)
{
    int i, j;
    char* str1 = new char[pos + 1];
    char* str2 = new char[len(str) - pos];
    
    for (i = 0, j = 0; i < pos; i++)
        str1[j++] = str[i];
    str1[j] = '\0';
    
    for (j = 0; i < len(str); i++)
        str2[j++] = str[i];
    str2[j] = '\0';
    
    cout << str1 << " and " << str2;
}

int main()
{
    #ifdef TC
        clrscr();
    #endif
    char* str1 = new char[MAXLEN];
    char* str2 = new char[MAXLEN];
    char* str3 = new char[2 * MAXLEN];
    int brpos;
    
    cout << "String termination character is tilde(~)." << endl << endl;
    cout << "Enter the first string (max. " << MAXLEN - 1<< "): ";
    cin.getline(str1, MAXLEN, '~');
    
    // Flush the buffer to avoid newline char appended to str2.
    cout << flush;  // Emptying buffer.
    cout << "Enter the second string (max. " << MAXLEN - 1<< "): ";
    cin.getline(str2, MAXLEN, '~');

    cout << endl << "Strlen(" << str1 << ") = " << len(str1);
    cout << endl << "Copied string is, " << copy(str3, str1);
    cout << endl << "Concatenation yielded, " << concat(str1, str2);
    cout << endl << "UpperCase(" << str1 << ") = " << ucase(str1);
    cout << endl << "LowerCase(" << str1 << ") = " << lcase(str1);
    cout << endl << "Comparison result, ";
    switch (compare(str1, str2)) {
        case -1:
            cout << str1 << " < " << str2;
            break;
        case 0:
            cout << str1 << " = " << str2;
            break;
        case 1:
            cout << str1 << " > " << str2;
            break;
    }
    
    do {
        cout << endl << "Enter first string's desired length: ";
        cin >> brpos;
    } while (brpos < 1 || brpos > len(str1));
    cout << "Two strings now constructed are, ";
    breakup(str1, brpos);

    cout << endl << endl << "Program over. Press any key to exit...";
    getch();
    return 0; // Successful termination.
}