Reversing a cstring array in a function using pointers c++ - c++

Question

I have an assignment that wants me to get a cstyle string (just 1 word) from the user then use a function to reverse its letters. The function has to take in 2 parameters, the first that is the destination string, and the other that is the source string. It will take whatever is in the source string, reverse it, then store the reversed version in the second string.
But everytime I compile, I typed in hello it prints out: \370\365\277\357\376. I just learned how to use pointers and cstyle strings so I don't really know how to use them and I think thats what is messing up my code. I'm dont understand it that well though so I cant figure out where I'm going wrong at.
Please let me know if you know what I'm doing wrong. Thank you!
#include <iostream>
#include <cstring>
#include <string>
#include <cctype>
using namespace std;
void IsPalindrome(char *cstring);
void Reverse(char *str2[], char *str1[]);
int main() {
// user variables
char str1[81];
char reverse;
char str2[81];
strcpy (str2, str1);
//prompt user to input string
cout << "\nPlease input a string (80 chars max): ";
cin >> str1;
cout << "\nYour string is: " << str1 << endl;
//call function
Reverse(str2[81], str1[81]);
//Output reversed string
cout << "Your string reversed is: " << str2 << endl;
cout << "This is a " << "." << endl;
return 0;
}
void Reverse(char *str2, char *str1)
{
char* front, *rear;
int len = strlen(str1);
char temp;
front = str1;
rear = &str1[len - 1];
while(front < rear)
{
temp = *front;
*front = *rear;
*rear = temp;
front++;
rear --;
}
}
void IsPalindrome(char cstring)
{
}

Answer 1

Pointers make life harder, don't use them if you don't need them. As your assignment is to reverse a string, so just use string. string is const char* inside but it's much easier to handle.
Beside your problem with pointers and arrays in your code, you are getting your string from input using std::cin. Remember that this way you can't get strings that have white space one them (you will just get the first word).
Also there is some algorithm that do this kind of tasks for you these days but for educational reasons it's not bad to do it yourself.
Here is what you can do, in the code I mentioned places that you could use ready to use algorithms to do the task for you.
#include <iostream>
#include <cstring>
#include <string>
#include <cctype>
#include <algorithm>
void Reverse(std::string &inputStr);
int main()
{
// user variables
std::string str1 = "";
std::cout << "\nPlease input a string (80 chars max): ";
std::getline(std::cin, str1);
std::cout << "\nYour string is: " << str1 << std::endl;
Reverse(str1);
//You also can use stl algorithm to reverse string for you and don't do it manually like below, but as it is an assignment it would not be good
//std::reverse(str1.begin(), str1.end());
//Output reversed string
std::cout << "Your string reversed is: " << str1 << std::endl;
std::cout << "This is a " << "." << std::endl;
system("pause");
return 0;
}
void Reverse(std::string &str)
{
int n = str.length();
for(int i = 0; i < n / 2; i++)
{
char temp = str[i];
str[i] = str[n - i - 1];
str[n - i - 1] = temp;
//You also can use stl algorithm to do the swap for you like below
//std::swap(str[i], str[n - i - 1]);
}
}
NOTE: This example will reverse your original string that user entered, if you want to have the both original and reversed, you need to pass a copy of input to the function. something like this :
std::string str2(str1);
Reverse(str2);
std::cout << "Reversed : " << str2;
EDIT: To match your assignment requirements (have a function with two parameters and single word string) you can easily change the above code like this :
void Reverse(std::string inputStr, std::string &outputStr);
int main()
{
// user variables
std::string str1 = "";
std::string str2 = "";
std::cout << "\nPlease input a string (80 chars max): ";
std::cin >>str1;
std::cout << "\nYour string is: " << str1 << std::endl;
Reverse(str1, str2);
//You also can use stl algorithm to reverse string for you and don't do it manually like below, but as it is an assignment it would not be good
//std::reverse(str1.begin(), str1.end());
//Output reversed string
std::cout << "Your string original is: " << str1 << std::endl;
std::cout << "Your string reversed is: " << str2 << std::endl;
system("pause");
return 0;
}
void Reverse(std::string inputStr, std::string &outputStr)
{
outputStr = inputStr;
int n = outputStr.length();
for(int i = 0; i < n / 2; i++)
{
char temp = outputStr[i];
outputStr[i] = outputStr[n - i - 1];
outputStr[n - i - 1] = temp;
//You also can use stl algorithm to do the swap for you like below
//std::swap(str[i], str[n - i - 1]);
}
}

Answer 2

There is no need of using pointers for reversing a character array to another character array.
void Reverse(char *str2, char *str1)
{
int len = strlen(str1);
for(int n = 0; n< len; n++)
{
str2[n] = str1[len-n-1];
}
}