Question

How would this code be translated into C#, specifically how would sprintf be implemented in C#?

string output = "The user %s logged in";
string loggedIn = "is";
string loggedOut = "isn't";

if (TheUser.CheckStatus())
{
    output = sprintf(output, loggedIn);
}
else
{
    output = sprintf(output, loggedOut);
}

return output;

I’m expecting to see "The user isn't logged in" if TheUser.CheckStatus() is false.

Answer 1

Check out string.Format and here is a version of your code using it:

string output = "The user {0} logged in";
string loggedIn = "is";
string loggedOut = "isn't";

if (TheUser.CheckStatus())
{
    output = string.Format(output, loggedIn);
}
else
{
    output = string.Format(output, loggedOut);
}

return output;

Or more simply: (using a ternary expression)

string output = "The user {0} logged in";

return TheUser.CheckStatus() 
    ? string.Format(output, "is")
    : string.Format(output, "isn't");