Doubt about strings

[Nebur]

Hey everyone I have the following question:

When I want to create a string s of size k if I do it like:
string s(k); I will get a compilation error.

However if I initialize the positions of the string with, for example, dots
string s(k, '.'); I get no error when compiling.

Why does this happen?

Is there a way of creating a string of fixed size without the need of initialising all the positions? Because it makes the program slower...

Thanks!

[Stormboy]

You are creating strings the wrong way. Strings doesn't need to be initialized with a size. These are not C strings. You could just do:

string s = "Bla bla bla I am boss muahhahahahaha";
string z;
cin >> z;
cout << "You entered: " << z << endl;

Doesn't matter. Strings don't have a fixed size.

[Nebur]

But I want to have a string with a precise size.

If I don't initialize it with that certain size, when trying to access a position I will get an invalid memory reference error.

[Catfish666]

Why does this happen?

If you look at the std::string constructors, you will see that there's no constructor that just takes the size. The closest is what you're already using, the "fill constructor".
http://www.cplusplus.com/reference/string/string/string/

If you don't want to fill the string with data, you could create then resize it.

std::string s;

s.resize(k);

Just an idea, perhaps you should look into std::vector if your strings are used to hold non-text data.

[Stormboy]

If you want strings with a precise size, you are then looking for C-Style strings.

Here is how to use them:

char s[25]; //Declare a string (a char array actually) of size 25. 

Just an example:

//C-Style string example
#include <iostream>

using namespace std;

int main()
{
    char name[15]; //Declare a char array (C-String) of size 15
    
    cout << "Please enter your name: ";
    cin >> name; //Use it like a normal string.
    cout << "Hello " << name << "!" << endl; //Can print it too.
    return 0;
}