Question

Write a modified version of the program below. In this version, you will dynamically allocate memory for the new C-string and old C-string, using the new keyword. Your program should ask the user for the size of the C-string to be entered, and ask the user for the C-string, then use new to create the two pointers (C-strings).   Then, call Reverse, as before. Don’t forget to use delete at the end of your program to free the memory!

#include <iostream>

#include <cstring>

using namespace std;

int Reverse(char * destination, const char * source, int num);

int main() // this is the test/driver code, for your function

{

const int STRINGSIZE = 10;

char oldCString[] = "Hello!";

char newCString[STRINGSIZE];

cout << "oldCString: " << oldCString << endl;

cout << "newCString before changing: " << oldCString << endl;

Reverse(newCString, oldCString, STRINGSIZE); // testing your function...

cout << "newCString after Reverse: " << newCString << endl;

return 0;

}

// Reverses a C-string passed in (source), and places the reversed

// C-string into (destination).

// (num) should represent the maximum valid length of (destination).

// If no null-zero character is found in (source) within (num-1)

// characters,the function will only read up to (num-1) characters

// from (source), and then copy the reversed characters to

// (destination) and append a null-zero to the end of it.

// The function will return the number of characters placed into

// (destination), including the null-zero.

// The function MUST use pointer notation (not array notation) inside

// it. However, you might find it useful to use array notation

// temporarily while developing the function, and then replace

// with pointer notation before turning in the assignment.

int Reverse(char * destination, const char * source, int num)

{

for (int x = 0; x < strlen(source); x++)

*( x + destination) = *( strlen(source) + source - 1 - x);

*(destination + strlen(source)) = '\0';

return 0;

}

Answer 1

#include <iostream>

#include <cstring>

using namespace std;

int Reverse(char * destination, const char * source, int num);

int main() // this is the test/driver code, for your function

{

int STRINGSIZE = 0;

cout<<"Enter size of C-string  : ";   //ask user for string size
cin>>STRINGSIZE;

char *oldCString = new char[STRINGSIZE];   //dynamic allocation of string using new keyword

cout<<"Enter a string : ";       //ask user to enter a string of STRINGSIZE entered previously
cin>>oldCString;

char *newCString = new char[STRINGSIZE];   //dynamic allocation of string using new keyword

cout << "oldCString: " << oldCString << endl;

cout << "newCString before changing: " << oldCString << endl;

Reverse(newCString, oldCString, STRINGSIZE); // testing your function...

cout << "newCString after Reverse: " << newCString << endl;

delete(oldCString); //deleting the memory allocated to oldCString
delete(newCString); //deleting the memory allocated to newCstring

return 0;

}

// Reverses a C-string passed in (source), and places the reversed

// C-string into (destination).

// (num) should represent the maximum valid length of (destination).

// If no null-zero character is found in (source) within (num-1)

// characters,the function will only read up to (num-1) characters

// from (source), and then copy the reversed characters to

// (destination) and append a null-zero to the end of it.

// The function will return the number of characters placed into

// (destination), including the null-zero.

// The function MUST use pointer notation (not array notation) inside

// it. However, you might find it useful to use array notation

// temporarily while developing the function, and then replace

// with pointer notation before turning in the assignment.

int Reverse(char * destination, const char * source, int num)

{

for (int x = 0; x < strlen(source); x++)

*( x + destination) = *( strlen(source) + source - 1 - x);

*(destination + strlen(source)) = '\0';

return 0;

}