How to repeat a string a variable number of times in C++?

Question

I want to insert 'n' spaces (or any string) at the beginning of a string in C++. Is there any direct way to do this using either std::strings or char* strings?

E.g. in Python you could simply do

>>> "." * 5 + "lolcat"
'.....lolcat'

Answer 1

std::string foo = std::string(5, '.') + "lolcat";

Check out std::string's constructors.

Answer 2

You should write your own stream manipulator

• http://www.two-sdg.demon.co.uk/curbralan/papers/WritingStreamManipulators.html

cout << multi(5) << "whatever" << "lolcat";

Answer 3

Use one of the forms of string::insert:

std::string str("lolcat");
str.insert(0, 5, '.');

This will insert "....." (five dots) at the start of the string (position 0).

Answer 4

There's no direct idiomatic way to repeat strings in C++ equivalent to the * operator in Python or the x operator in Perl. If you're repeating a single character, the two-argument constructor (as suggested by previous answers) works well:

std::string(5, '.')

This is a contrived example of how you might use an ostringstream to repeat a string n times:

#include <sstream>

std::string repeat(int n) {
    std::ostringstream os;
    for(int i = 0; i < n; i++)
        os << "repeat";
    return os.str();
}

Depending on the implementation, this may be slightly more efficient than simply concatenating the string n times.

Answer 5

I know this is an old question, but I was looking to do the same thing and have found what I think is a simpler solution. It appears that cout has this function built in with cout.fill(), see the link for a 'full' explanation

http://www.java-samples.com/showtutorial.php?tutorialid=458

cout.width(11);
cout.fill('.');
cout << "lolcat" << endl;

outputs

.....lolcat