Could someone explain in detail on how this palindrome code works?

Question

 #include <iostream>

// Define is_palindrome() here:
bool is_palindrome(std::string text) {

std::string reversed_text = "";

for (int i = text.size() - 1; i >= 0; i--) {
reversed_text += text[i];
}

if (reversed_text == text) {
return true;
}

return false;

}

int main() {

std::cout << is_palindrome("madam") << "\n";
std::cout << is_palindrome("ada") << "\n";
std::cout << is_palindrome("lovelace") << "\n";

}

Could someone please explain to me in great detail on how this for loop works? I would like to know how the code sequences each letter to figure out if the word is a palindrome.

Answer 1

To begin, we define the is_palindrome function to return a bool. Our input string is the function parameter.

Then, we reverse the text using the following for loop.

std::string reversed_text = "";

for (int i = text.size() - 1; i >= 0; i--) {
reversed_text += text[i];
}

This code simply defines a string called reversed_string. It then reverses the input string one letter at a time ( text[i] gives the i+1 letter in the input string, reversed_text += text[i] adds this letter to the string).

After that, the code is a simple if statement. It compares the original string and the reversed string. If both are the same, the function returns true. If they are not the same, the function returns false.

if (reversed_text == text) {
return true;
}

return false;

}

Answer 2

The ability to read code is far more important than the ability to write it, as in most of your programming life, you will read a lot more than write. More often than not, it's someone else's code. If you lack the skill, you will have a hard time working in this field.

Here's above function body commented:

// prepare a string variable to hold the reversed input
std::string reversed_text = "";

// append each character from the input to variable above, starting from the last character, effectively generating its reversed version
for (int i = text.size() - 1; i >= 0; i--) {
reversed_text += text[i]; 
}

// it's a palindrome if the reversed input is the same as the input
if (reversed_text == text) {
return true;
}

// not a palindrome otherwise
return false;