Invalid conversion from 'char' to 'char*' while calling a function (c++)

Question

every time I write loadChar(charVariable,positonOfCharacter) with this code:

bool LoadEntity::loadChar(char * outputChar,int position)
    {
        ifstream file(nameOfFile.c_str());

        if(!(file.good()))
            return false;

        file.seekg(position);
        if(file.get())
        {
            * outputChar = file.get();
            return true;
        }
        else
            return false;
    }`

I get this error: invalid conversion from 'char' to 'char* The code is supposed to return bool if the function was ran correctly and change the value of char outputChar to character in file on int position. What causes this problem?

You need to pass a pointer, not a character by value. The error is self explanatory. — Matthieu Brucher, Dec 08 '18 at 16:01
Please [get a couple of good books](https://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list/388282#388282), and learn about *references*. — Some programmer dude, Dec 08 '18 at 16:02
Please note that you call `file.get()` two times, hence you read two _different_ values. — Thomas Lang, Dec 08 '18 at 16:03
Change to `bool LoadEntity::loadChar(char& outputChar,int position)` and treat `outputChar` like a normal variable (i.e. no need to dereference). — not an alien, Dec 08 '18 at 16:03

Christophe · Accepted Answer · 2018-12-08T16:50:03.977

Problem:

char charVariable;
...
loadChar(charVariable, positonOfCharacter);

Here you are trying to pass a char value instead of the pointer (i.e. char*) that is expected by the function. This is illegal.

Easy solution:

Use the address of your variable when you call the function:

loadChar(&charVariable, positonOfCharacter);    // note the &

Alternative:

If you're not so familiar with pointers you could also change the function's signature and use a reference instead of a pointer. References allow you to change the value of the original variable:

bool LoadEntity::loadChar(char& outputChar, int position)  // note the &
{
    ... 
        outputChar = file.get();      // note: no * anymore
    ...
}

Unrelated issue:

There's a problem with your use of get(). The following will lead you to read twice the file but ignore the first input:

    if(file.get())
    {
        * outputChar = file.get();
        ...
    }

In addition, if no char is available the if might nevertheless be executed and return ture, as there is no guarantee that the function will return 0.

Prefer :

    if(file.get(*outputChar))
    {
        return true;
    }

Don't worry: the output char will not be changed if no char can't be read from the file.

Invalid conversion from 'char' to 'char*' while calling a function (c++)

1 Answers1

Problem:

Easy solution:

Alternative:

Unrelated issue:

Related