using an index number, append that index (a character) to char array

Question

I'm attempting to do something like this.

class testClass {        
  public:              
    void testFunction(char charArray[])
    {
    char output[].append(charArray.at(1));
    char output[].append(charArray.at(7));
    char output[].append(charArray.at(3));
    cout << output;
    }


int main() {
  testClass testObject;
  testObject.testFunction("Flowers"); 
  return 0;
}
   


}

What it's meant to do is:

get the Letters 'F', 'S' and 'O' from the char array from an index number
append that char to the output chararray

It's been frustrating since I've went from strings, to *chars, and char arrays.

Not really sure what the simpliest easiest solution is. Yes, I want to retain 1 char at a time from that string. It was just meant to be a fun project but it's way more complicated than I thought it'd be

expected output:

FSO

Arrays of `char` don't have the functionality contained in `std::string`. The only thing a char array can do is set individual elements. — Camwin, Jul 02 '21 at 21:02
_It's been frustrating since I've went from strings, to *chars, and char arrays._ Yes, it would be, why did you do that? — Paul Sanders, Jul 02 '21 at 21:03

score 1 · Accepted Answer · answered Jul 02 '21 at 21:03

1

Do you mean like this:

#include <string>
#include <iostream>

class testClass {        
  public:              
    void testFunction(const std::string& charArray)
    {
    std::string output;
    output.push_back(charArray.at(0));
    output.push_back(charArray.at(6));
    output.push_back(charArray.at(2));
    std::cout << output;
    }
};

int main() {
  testClass testObject;
  testObject.testFunction("Flowers"); 
  return 0;
}

Of course C++ like any sane language uses zero-based indexes.

answered Jul 02 '21 at 21:03

Quimby

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Thank you, I was pulling my hair out over this. :/ in what way does string& differ from string? is it some type of pointer? – Intro verb Jul 02 '21 at 21:05
No problem, I can explain some parts in more detail if you need, or if there was anything in particular that was tripping you up. – Quimby Jul 02 '21 at 21:07
@TedLyngmo I can't yet. but I'm going too. – Intro verb Jul 02 '21 at 21:07
@Quimby I'm unsure what the string& means exactly. is it some type of pointer? – Intro verb Jul 02 '21 at 21:08
@Introverb It is a reference to a string, yes it is similar to a pointer. See answers e.g. [here](https://stackoverflow.com/questions/57483/what-are-the-differences-between-a-pointer-variable-and-a-reference-variable-in). It is used here to prevent making an extra copy of the string parameter because all parameters are copied/moved by default, C++ does not have implicit reference semantics for classes like Java does. IF you are learning C++, I can recommend a curated [list of recommended books](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list). – Quimby Jul 02 '21 at 21:09

using an index number, append that index (a character) to char array

1 Answers1