重复存储在变量中的字符串x次

Question

I am looking to print a string stored in a variable multiple times. In python I would be able to do this simply by using something like this:

l1= "*" * width l2= "*" + (" " * (width-2)) + "*\\n" l3= l2 * ((height-4)/2)

Where height and width are provided as inputs by the user. Ultimately there are several other lines of code like this that will print a rectangle of *s.

Is there a simple way to do this in C++?

I tried using l2= std::string((height-4)/2, l1); , but this causes an error since C++ want a string in place of L2. (l1 is formatted using the std::string() function and works properly.

Any help is greatly appreciated.

Answer 1

std::string has a constructor that takes a character and a repetition argument, which you can use directly to generate the top and bottom lines, something like:

std::string l1 = std::string(width, '*') + "\n";

Likewise, the "middle" lines could be generated something like this:

std::string l2 = "*" + std::string(width-2, ' ') + "*\n";

As for putting the pieces together into a square goes, I'd probably use std::generate_n to generate the middle lines, so the code would look something like this:

auto l1 = std::string(width, '*') + "\n";
std::cout <<  l1;
std::generate_n(std::ostream_iterator<std::string>(std::cout), 
    height-2,
    [=] {return "*" + std::string(width - 2, ' ') + "*\n"; });
std::cout << l1;

If you really need the result in a string instead of being written to cout , you can substitute a ostringstream in place of cout , and write to it, then use its str() member to get the content as an std::string .

Answer 2

You could create a simple helper function to perform the task if you wanted:

Example:

string stringMultiplier(string startString, int multiplier){
    string endString = startString;
    for (int i=1; i<multiplier; i++){
        endString = endString + startString;
    }
    return endString;
}

int main()
{
   cout << stringMultiplier("*",4) << endl; 
   return 0;
}