C++ forbids converting a `string` constant to `char*` - Alphabets to Morse converting program [duplicate]

Question

So i was working on this assignment, i need to convert normal text into Morse code. We're studying basic c++ at the moment so I'm not allowed to use the string data type or any other complex built-in functions.So I tried doing it through a char array. When i try running it,the following error shows up " ISO C++ forbids converting a string constant to 'char*' "

#include <iostream>
using namespace std;

int len = 0;
char string[45] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '.', ',', '?', '[', '!', '(', ')', '&' };
char* morse[45] = { ".-", "-...", "-.-.", "-..", ".", "..-.", "--.", "....", "..", ".---", "-.-", ".-..", "--", "-.", "---", ".--.", "--.-", ".-.", "...", "-", "..-", "...-", ".--", "-..-", "-.--", "--..", "-----", ".----", "..---", "...--", "....-", ".....", "-....", "--...", "---..", "----.", ".-.-.-", "--..--", "..--..", ".----.", "-.-.--", "-..-.", "-.--.", "-.--.-", ".-..." };

void size(char* arr)
{
    for (int i = 0; arr[i] != 0; i++) {
        len++;
    }
}

int main()
{
    char str[100];
    cout << "Enter string: ";
    cin.getline(str, 100);
    size(str);
    for (int i = 0; i < len; i++) {
        for (int j = 0; j < 45; j++) {
            if (str[i] == string[j]) {
                cout << morse[j];
                break;
            }
        }
    }
    return 0;
}

Answer 1

You're defining an array of char* objects. You initialize those pointers with string literals. But as the error explains, converting a string literal (called constant by the compiler) to char* is not allowed.

Solution: Converting a string literal to const char* is allowed, so you could declare an array of const char* instead. You don't appear to modify the strings pointed by the array, so this shouldn't be a problem.

---

PS. You've chosen to include a standard library header, and have chosen to use using namespace std; and defined an identifier with the same name as an identifier declared by the standard library (string). That will very likely be a problem for the compiler.

Solution: Do not use using namespace std.

Workaround: Come up with another variable name than string. The trick is to know all identifiers declared by the standard library. Since this trick isn't trivial and new identifiers will be added in future versions of the standard, I recommend the solution above instead.

Answer 2

The issue, as described in the error, is that "...", for example, is a string constant and you are trying to assign to a non-constant char*. Instead you should be assigning to a const char*:

const char* morse[45] = { ".-" // ...