(string)char typecast

Question

I want to cast a char to a string with this function:

int charIndexDistance (char a, char b)
{
    if (indexical) {
        string test_a = convertOntology((string)a, 0);
        string test_b = convertOntology((string)b, 0);
        cout << test_a << " " << test_b << endl;

        int test = abs(char_index[a] - char_index[b]);
        return test; //measure indexical distance between chars
    } else 
        return 1;
}

but I get this "error C2440: 'type cast' : cannot convert from 'char' to 'std::string"

what is thr problem? and how is a char cast to a string - should I use string append?

also, the cout and int test are for debugging purposes and will be removed later

score 4 · Accepted Answer · edited May 23 '17 at 10:32

There simply is no such conversion. Instead, you have to construct a string manually:

string(1, a)

This uses the constructor taking a length and a char to fill the string with.

In the context of your code:

string test_a = convertOntology(string(1, a), 0);
string test_b = convertOntology(string(1, b), 0);

Even if an appropriate constructor / cast existed your code would be bad since you should avoid C-style casts in C++. The situation would call for a static_cast instead.

score 2 · Answer 2 · answered Mar 05 '13 at 17:06

2

A char is not a string.

A char is also not a null-terminated string.

A null-terminated string is a char array with the null character at the end.

answered Mar 05 '13 at 17:06

StoryTeller - Unslander Monica

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so I could have done something like `char a; string a_test = 'a' + '\n'` – forest.peterson Mar 06 '13 at 00:55
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@forest No, since adding two `char`s doesn’t concatenate them, it adds their byte value. But you can concatenate an (empty) string and a `char`: `string() + 'a'` works (but is probably less efficient than my code). Note that `"" + 'a'` does *not* work, since `""` is *not* a string, it’s a null-terminated `char` array. – Konrad Rudolph Mar 06 '13 at 09:47

score 0 · Answer 3 · answered Mar 05 '13 at 17:09

0

Replace (string)a with string(1,a)

answered Mar 05 '13 at 17:09

Happy Green Kid Naps

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score 0 · Answer 4 · edited Sep 02 '21 at 07:09

0

Everything already mentioned works, but you may also want to try:

char mychar = 'A';
string single_char = "";
string += mychar;

Hope that helps!

edited Sep 02 '21 at 07:09

Ibrahim

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answered Feb 01 '15 at 04:49

Luis Serota

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(string)char typecast

4 Answers4