cannot convert argument 2 from 'std::string *' to 'std::string'

Question

Not sure why this is happening, it seems like everything is lined up the way it should be unless there is something I am missing. I can't pass these variables and no matter what I try to throw at the compiler, it just gives me another error.

This is my code so far.

void parse(string name, string storage_1, string storage_2, string storage_3)
{//some code
}

//some more code

int start = 0;
int length = 0;
string param_1, param_2, param_3;



while (!infile.eof())
{
    if (!infile)
    {
        cout << "ERROR: File " << file << " could not be located!" << endl << endl;
        break;
    }

    param_1.clear();
    param_2.clear();
    param_3.clear();
    line_input.clear();

    getline(infile, line_input);

    parse(line_input, &param_1, &param_2, &param_3);

    cout << param_1 << endl << param_2 << endl << param_3 << endl << endl;
}

Any particular reason you're doing &param_x instead of simply param_x? — David G
– David G, Commented Oct 17, 2014 at 1:53
The compiler error says it: You are passing pointers to your parse function, but it expects strings. — Oguk
– Oguk, Commented Oct 17, 2014 at 1:53
Then make the parameters of type std::string& and do not use an & when calling. In other words, call as follows: "parse(line_input, param_1, param_2, param_3)." — Benilda Key
– Benilda Key, Commented Oct 17, 2014 at 1:56
You should be checking the result of getline before using the string, not just checking for eof every so often. — Qaz
– Qaz, Commented Oct 17, 2014 at 1:59

Remy Lebeau · Accepted Answer · 2014-10-17 02:00:41Z

2

In the function declaration:

void parse(string name, string storage_1, string storage_2, string storage_3)

The second, third, and forth arguments are a string passed by value.

But in the function call:

string param_1, param_2, param_3;
parse(line_input, &param_1, &param_2, &param_3);

You are passing addresses to these strings (pointers).

You may change the declaration to:

void parse(string name, string* storage_1, string* storage_2, string* storage_3)

Or change the function call to use references:

void parse(string name, string& storage_1, string& storage_2, string& storage_3)
parse(line_input, param_1, param_2, param_3);

edited Oct 17, 2014 at 2:00

Remy Lebeau

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answered Oct 17, 2014 at 1:58

icemoon1987

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Remy Lebeau · Accepted Answer · 2014-10-17 01:58:10Z

The error is self-explanatory. You are passing pointers where pointers are not expected. Specifically, you are using the & operator to pass your parameter values to parse(), but it does not want pointers.

Since parse() is intended to output the parsed values, you need to either:

change parse() to use references, and remove the & operator when calling parse():

void parse(string name, string &storage_1, string &storage_2, string &storage_3)
{
    //some code
    storage_1 = ...;
    storage_2 = ...;
    storage_3 = ...;
}

parse(line_input, param_1, param_2, param_3);

change parse() to work with pointers instead, and keep the & operator:

void parse(string name, string *storage_1, string *storage_2, string *storage_3)
{
    //some code
    *storage_1 = ...;
    *storage_2 = ...;
    *storage_3 = ...;
}

parse(line_input, &param_1, &param_2, &param_3);

If all three parameters are required, use #1. If any of the parameters can be optional use #2.

Remy Lebeau · Accepted Answer · 2014-10-17 02:00:59Z

0

In your call to parse, you are passing &param_1, which creates a string*, instead of plain param_1, which would be the string that your function expects.

edited Oct 17, 2014 at 2:00

Remy Lebeau

610k36 gold badges516 silver badges875 bronze badges

answered Oct 17, 2014 at 1:58

Oguk

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