Question

You are required to use C++ static or dynamic arrays of characters to store c-strings. You are NOT allowed to use any C++ string data type variable for any purpose. Moreover, you are allowed to add any include directive. You are not allowed to include string, cstdlib or math libraries. Also, you are not allowed to use any built-in functions of c-strings.

can someone help with the third, fourth, and fifth functions? I tried many ways but i cannot figure them out...i don't know how to search char array and arrangement of range. I need it urgently.

typedef char* charPointer;

int cstrlen(const charPointer& s)
{
  int i = 0;
   int count = 0;
   while (s[i] != '\0')
   {
       count++;
       i++;
   }
   return count;
}

int countChars(const charPointer& s, const char& ch)
{
int count = 0;
   cstrlen;
   for (int i = 0;i < cstrlen(s); i++)
   {
       if (s[i] == ch)
       {
           count++;
       }
   }
   return count;
}

int findChar(const charPointer& s, const char& ch, const int& startIndex = 0, const int& lastIndexTemp = -1)
{
   /*
   returns the smallest index where the character ch is found in s starting from
   startIndex (inclusive) upto lastIndex (exclusive). The default argument value
   for startIndex is 0. The default argument value for lastIndexTemp is -1 in which
   case cstrlen(s) must be used instead of -1.
   For example,
       findChar("test", 't', 1, 4) must return 3. Here startIndex = 1, lastIndex = 4
       findChar("test", 't', 3) must return 3. Here startIndex = 3, lastIndex = 4
       findChar("test", 't', 1, 3) must return -1. Here startIndex = 1, lastIndex = 3
       findChar("test", 't') must return 0. Here startIndex = 0, lastIndex = 4
   If ch is not found in s in the given interval, the the function must return -1
   This function must first validate both the startIndex and lastIndex.
   That is, if lastIndex > cstrlen(s) or startIndex < 0 it must return -1
   */
}

charPointer getCopy(const charPointer& s)
{
   /*
   returns a new cstring that is a copy of the cstring s.
   That is a new cstring with as big memory as the size of
   the cstring s is created and then all the characters of
   s including the null char are copied to it.
   */
}

void rotateString(const charPointer& s, const int& r)
{
   /*
   Rotates the characters of s by r units
       If r > 0, rotate the characters of s to the left
       If r < 0, rotate the characters of s to the right
       Please note the value of r can be any integer even larger than the length of s
       For example,
           "asmara" rotated to the left by 0 becomes "asmara"
           "asmara" rotated to the left by 1 becomes "smaraa"
           "asmara" rotated to the left by 2 becomes "maraas"
           "asmara" rotated to the left by 3 becomes "araasm"
           "asmara" rotated to the left by 4 becomes "raasma"
           "asmara" rotated to the left by 5 becomes "aasmar"
           "asmara" rotated to the left by 6 becomes "asmara"
           "asmara" rotated to the left by 7 becomes "smaraa"
           "asmara" rotated to the left by 8 becomes "maraas"

       similarly
           "asmara" rotated to the right by 0 becomes "asmara"
           "asmara" rotated to the right by 1 becomes "aasmar"
           "asmara" rotated to the right by 2 becomes "raasma"
           "asmara" rotated to the right by 3 becomes "araasm"
           "asmara" rotated to the right by 4 becomes "maraas"
           "asmara" rotated to the right by 5 becomes "smaraa"
           "asmara" rotated to the right by 6 becomes "asmara"
           "asmara" rotated to the right by 7 becomes "aasmar"
           "asmara" rotated to the right by 8 becomes "raasma"

           and etc…
   */
}

int main()
{
   /*
   This main program is designed to test the functions you need to implement.
   You should NOT remove any line of code from this main program.
   But you may add more test code in the main program if you like.
   */
   cout << "This program is designed to help you test your functions." << endl;
   srand(time(0));

   //Test cstrlen function
   cout << endl << "Testing cstrlen function";
   cout << endl << "------------------------" << endl;
   char s1[] = "irregular";
   cout << "The length of s1=\"" << s1 << "\" is " << cstrlen(s1) << endl;
   char emptyCstr[] = "";
   cout << "The length of \"\" is " << cstrlen(emptyCstr) << endl;

   //Test countChars functions
   cout << endl << "Testing countChars function";
   cout << endl << "---------------------------" << endl;
   char ch = 'r';
   int count = countChars(s1, ch);
   cout << "ch='" << ch << "' is found in s1=\"" << s1 << "\" " << count << " times." << endl;

   /*//Test findChar functions
   cout << endl << "Testing findChar function";
   cout << endl << "-------------------------" << endl;
   int a = 2, b = cstrlen(s1);
   int index = findChar(s1, ch, a, b);
   cout << "ch='" << ch << "' is found in s1=\"" << s1 << "\" in the index interval [" << a << ", " << b << ") at index " << index << endl;
   a = 3;
   index = findChar(s1, ch, a);
   cout << "ch='" << ch << "' is found in s1=\"" << s1 << "\" in the index interval [" << a << ", " << b << ") at index " << index << endl;
   b = 8;
   index = findChar(s1, ch, a, b);
   cout << "ch='" << ch << "' is found in s1=\"" << s1 << "\" in the index interval [" << a << ", " << b << ") at index " << index << endl;
   index = findChar(s1, ch);
   cout << "ch='" << ch << "' is found in s1=\"" << s1 << "\" in the index interval [0, " << cstrlen(s1) << ") at index " << index << endl;

//Test getCopy function
   cout << endl << "Testing getCopy function";
   cout << endl << "------------------------" << endl;
   char* s2 = getCopy(s1);
   cout << "A copy of \"irregular\" is s2=\"" << s2 << "\"" << endl;
   char* s3 = getCopy(s2);
   cout << "A copy of s2=\"" << s2 << "\" is s3=\"" << s3 << "\"" << endl;
   delete[] s2;
   s2 = new char('\0');
   cout << "s2 is modified to s2=\"" << s2 << "\" but s3 is still s3=\"" << s3 << "\"" << endl;
   delete[] s3;
   s3 = getCopy(s2);
   cout << "A copy of s2=\"" << s2 << "\" is s3=\"" << s3 << "\"" << endl;

   //Test rotateString function
   cout << endl << "Testing rotateString function";
   cout << endl << "-----------------------------" << endl;
   char s4[] = "asmara";
   for (int i = 0; i < 10; i++)
   {
       int r = rand() % 101 - 50;
       if (r > 0)
           cout << "s4=\"" << s4 << "\" rotated " << r << " times to the left becomes ";
       else
           cout << "s4=\"" << s4 << "\" rotated " << -r << " times to the right becomes ";
       rotateString(s4, r);
       cout << "\"" << s4 << "\"" << endl;
   }

return 0;

}

Answer 1

Code:

//findchar
int findChar(const charPointer& s, const char& ch, const int& startIndex = 0, const int& lastIndexTemp = -1)
{
    /*
   returns the smallest index where the character ch is found in s starting from
   startIndex (inclusive) upto lastIndex (exclusive). The default argument value
   for startIndex is 0. The default argument value for lastIndexTemp is -1 in which
   case cstrlen(s) must be used instead of -1.
   For example,
       findChar("test", 't', 1, 4) must return 3. Here startIndex = 1, lastIndex = 4
       findChar("test", 't', 3) must return 3. Here startIndex = 3, lastIndex = 4
       findChar("test", 't', 1, 3) must return -1. Here startIndex = 1, lastIndex = 3
       findChar("test", 't') must return 0. Here startIndex = 0, lastIndex = 4
   If ch is not found in s in the given interval, the the function must return -1
   This function must first validate both the startIndex and lastIndex.
   That is, if lastIndex > cstrlen(s) or startIndex < 0 it must return -1
   */
    int lastIndex = lastIndexTemp;
    if(lastIndexTemp==-1){
        lastIndex=cstrlen(s);
    }
    if(lastIndex > cstrlen(s) || startIndex < 0){
        return(-1);
    }

    for (int i=startIndex;i<lastIndex;i++){
        if(s[i]==ch){
            return(i);
        }
    }
    return(-1);

}


//getCopy funtion
charPointer getCopy(const charPointer& s)
{
     /*
   returns a new cstring that is a copy of the cstring s.
   That is a new cstring with as big memory as the size of
   the cstring s is created and then all the characters of
   s including the null char are copied to it.
   */
    int len = cstrlen(s);
    char *t = new char[len+1];
    for(int i=0;i<len;i++){
        t[i]=s[i];
    }
    t[len]='\0' ;
    return(t);
}

//rotateString funtion

void rotateString(const charPointer& s, const int& r)
{
   /*
   Rotates the characters of s by r units
       If r > 0, rotate the characters of s to the left
       If r < 0, rotate the characters of s to the right
       Please note the value of r can be any integer even larger than the length of s
       For example,
           "asmara" rotated to the left by 0 becomes "asmara"
           "asmara" rotated to the left by 1 becomes "smaraa"
           "asmara" rotated to the left by 2 becomes "maraas"
           "asmara" rotated to the left by 3 becomes "araasm"
           "asmara" rotated to the left by 4 becomes "raasma"
           "asmara" rotated to the left by 5 becomes "aasmar"
           "asmara" rotated to the left by 6 becomes "asmara"
           "asmara" rotated to the left by 7 becomes "smaraa"
           "asmara" rotated to the left by 8 becomes "maraas"

       similarly
           "asmara" rotated to the right by 0 becomes "asmara"
           "asmara" rotated to the right by 1 becomes "aasmar"
           "asmara" rotated to the right by 2 becomes "raasma"
           "asmara" rotated to the right by 3 becomes "araasm"
           "asmara" rotated to the right by 4 becomes "maraas"
           "asmara" rotated to the right by 5 becomes "smaraa"
           "asmara" rotated to the right by 6 becomes "asmara"
           "asmara" rotated to the right by 7 becomes "aasmar"
           "asmara" rotated to the right by 8 becomes "raasma"

           and etc…
   */

   int ln = cstrlen(s);
   int rc = r%ln; //getting original count of rotation
   if(r<0){
        rc = (-r);
        rc=rc%ln;
        rc=ln-rc;
   }
   char res[ln];
   int ind;
   for(int i = 0; i<ln ; i++ ){
        ind = (rc+i)%ln;
        res[i] = s[ind];
   }

   for(int i=0;i<ln;i++){
        s[i]=res[i];
   }
   delete [] res;

}

Output:

Testing findChar function
-------------------------
ch='r' is found in s1="irregular" in the index interval [2, 9) at index 2
ch='r' is found in s1="irregular" in the index interval [3, 9) at index 8
ch='r' is found in s1="irregular" in the index interval [3, 8) at index -1
ch='r' is found in s1="irregular" in the index interval [0, 9) at index 1

Testing getCopy function
------------------------
A copy of "irregular" is s2="irregular"
A copy of s2="irregular" is s3="irregular"
s2 is modified to s2="" but s3 is still s3="irregular"
A copy of s2="" is s3=""

Testing rotateString function
-----------------------------
s4="asmara" rotated 40 times to the left becomes "raasma"
s4="raasma" rotated 40 times to the right becomes "asmara"
s4="asmara" rotated 21 times to the left becomes "araasm"
s4="araasm" rotated 37 times to the left becomes "raasma"
s4="raasma" rotated 30 times to the left becomes "raasma"
s4="raasma" rotated 25 times to the right becomes "araasm"
s4="araasm" rotated 47 times to the left becomes "maraas"
s4="maraas" rotated 40 times to the left becomes "asmara"
s4="asmara" rotated 2 times to the left becomes "maraas"
s4="maraas" rotated 30 times to the right becomes "maraas"

_______________________

Hope it Helps.