C++ passing array of strings to a function

Question

So I want to pass an array of std::strings to a function. The number of std::strings in the array is predefined via preproc. directives. The whole thing should look like this:

#define ARRAYSIZE 3
void foo(std::string[ARRAYSIZE]);
void foo(std::string instrings[ARRAYSIZE])
{
...
}

Question: Can I call on the function without having to save the std::string array first to a variable, and then calling with that? So basically I want to call it with one line, like:

void main()
{
...
foo( std::string x[ARRAYSIZE] = {"abc","def","ghi"}  );
...
}

Problem is that I can't figure out the correct syntax of the function call (I'm not even sure there is one), visual studio's intellisense keeps shooting my ideas down.

#define for constants is totally unnecessary. Use const or constexpr instead. — Qaz
– Qaz, Commented Jul 7, 2014 at 1:09
@chris I'd say it depends on the scope. If I am to use the same array length on multiple unrelated functions, and the length must be exactly the same I'd use a define. But then again it's not exactly best practice, and this comes from a C perspective... at the end of the day, it doesn't really matter. — rath
– rath, Commented Jul 7, 2014 at 1:12
@rath, You can use a global constant if you really need to. At least it's actually an object that obeys scoping rules and not just text being replaced. — Qaz
– Qaz, Commented Jul 7, 2014 at 1:14

Cheers and hth. - Alf · Accepted Answer · 2014-07-07 03:01:09Z

3

If you would like to switch to std::vector that can be constructed on the fly as you have mentioned in the comment to the question, this should work (works with gcc):

void foo(const std::vector<std::string> &stringVec)
{
}

int main()
{
    foo( std::vector<std::string>({"abc","def","ghi"}));
}

edited Jul 7, 2014 at 3:01

Cheers and hth. - Alf

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answered Jul 7, 2014 at 1:25

Ilya Kobelevskiy

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1 Comment

CivDav Over a year ago

Thanks, this works! :) I had to rewrite foo so it expects a vector, which means the compiler doesn't check the array's size anymore, it accepts any vector of strings, but I can just check it myself and give some horrible error message if the size is not ARRAYSIZE

Cheers and hth. - Alf · Accepted Answer · 2014-07-07 03:01:52Z

1

One way to pass multiple values like this {x0,x1,x2,...} would be to use std::initializer_list which was introduced in c++11. Although this way it is not possible to force a constant number of values.

void foo(const std::initializer_list<std::string>& input) {

}

int main() {
    foo({"abc","def","ghi"});
}

edited Jul 7, 2014 at 3:01

Cheers and hth. - Alf

146k15 gold badges218 silver badges342 bronze badges

answered Jul 7, 2014 at 1:45

Maurice

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