C++ problem. I have this main.cpp and string.h files to check if a string is a p

Question

C++ problem. I have this main.cpp and string.h files to check if a string is a palindrome or not . example Output is below.

I am getting a terminate called after throwing an instance of 'int'   , Aborted , this happens after i do g++ main.cpp "avid diva". How do I fix this, or where do i get started to prevent this. Below is the main.cpp file followed by the string.h file. I am creating my own string class.

#include <cstdlib> // exit
#include <cctype> // tolower
#include <iostream> // cout
#include "string.h" // String class
using namespace std;
bool isPalindrome(String A){
int i, length=0;
  
//gets char length
int j = 0;
while (A[j] != '') {
    ++j;
}
length = j;

// palindrome function
for(i=0;i < length ;++i){
    if(A[i] != A[length-i-1]){
      return false;
       break;
    }
    }
return true;
}

int main(int argc, char *argv[]) {
// check for the right number of cmd args
// and exit if not properly included
if (argc != 2) {
    cout << "You must enter one string as an argument!" << endl;
    exit(1);
}
// Here's the command line argument string
String stringA(argv[1]);
// check if it's a palindrome
if (isPalindrome(stringA)) {
    // if so, then print that fact
    cout << stringA << " is a palindrome" << endl;
    // append the reversed string
    // stringA.append(stringA.reversed());
    // and we have another palindrome
    cout << "so is " << stringA << endl;;
} else {
    // otherwise, print that fact
    cout << stringA << " is not a palindrome" << endl;
    // append the reversed string
    // stringA.append(stringA.reversed());
    // and magically we have a palindrome from a non-palindrome!
    cout << "but " << stringA << " is" << endl;
}
return 0;
}

string.h file

#ifndef string
#define string

class String {
public:
String(); // create an empty String object
String(const char *); // create a String object from a C-style string
String (const char); // create a String object from a single char
int length() const; // return the number of characters in the string (not including null-termination)
~String (); // destructor of the class, frees heap memory
void append(const String &); // insert characters at the end of the String but before the null-term
String reversed() const; // return a new String object with the characters in reverse order
char & operator[](int) const; // access the character at a given index
const char * c_str() const; // return a C-style string with the same characters in the same order
friend std::ostream & operator<<(std::ostream &, const String &); // allow for use with cout
char* info;
int size;
};

int String:: length() const{
/*   int j = 0;
    while (info[j] != '') {
        ++j;
    }
    size = j;*/
return size;
}

std::ostream & operator<<(std::ostream & out, const String &S){
if (S.length() > 0)   {
    for (int i=0; i < S.length(); i++)
      out << S[i];
} else out << "";
return out;
}

String String:: reversed() const{
//void backword(char word[20])
String word (info);
int i=0,j=0;
char temp;
j= word.size -1;
// j=size(word)-1;
while(i<j) {
    temp=word[i];
    word[i]=word[j];
    word[j]=temp;
    i++;
    j--;
}
return word;
}

String:: String(){
size = 0;
info   = new char[0];
}
      
String:: String(const char C){
size= 1;
info = new char[sizeof(char) * 1];
info[0] = C;
/* adding null-character to make it CStyle string */
info[1] = '';
  
  
  
}
  
String:: String(const char *C){
if (C) {
    int m = 0;
    while (C[m] != '') m++;
    size = m;
    info = new char[size * sizeof(char)];
    for (int i=0; i < m; i++){
      info[i] = C[i];
    }
    info[size] = '';
} else {
    size = 0;
    info = new char[0];
    info[0] = '';
}
}
  
char & String::operator[] (int i) const {
if (i >= size) throw 1;
return info[i];
}

const char * String::c_str() const {
/* type cast to const char * and return it */
return static_cast<const char *>(info);
}

String::~String() {
/* freeing allocated memory by new keyword */
if (info) {
    delete info;
}
}
  
void String::append(const String & obj) {
if (info) {
    int new_len = obj.size + size;
    char * new_info = new char[new_len];
    int i;
    for (i = 0; i < size; ++i) {
      new_info[i] = info[i];
    }
    for (i = 0; i < obj.size; ++i) {
      new_info[size + i] = obj[i];
    }
    new_info[new_len] = '';
    delete info;
    info = new_info;
}
}
  
#endif

Explanation / Answer

change this function in String.h file to this code:

char & String::operator[] (int i) const {
if (i > size) throw 1;
return info[i];
}

please give thumbs up, thanks

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