如何将带有字符串变量的字符串传递给C ++中的函数

Question

I have a function with default Parameters which displays text to screen. Something like this:

DrawScreenString(int, int, string, int uicolor, font);

I am however trying to pass in a string variable "livesRemaining" like so:

DrawScreenString(10, 5, "Lives  : %d ",livesRemaining, 0xF14040, NULL);
livesRemaining = 3

So due to the fact that the function only takes in 5 arguments, it fails to compile, because the function thinks that i'm trying to pass in a 6th argument not knowing i'm trying to add string to the already existing string "Lives :"

This is what i want the result to look like:

Live   : 3

I know this is not the right way of doing this, how do i do it ? Thanks a bunch !!

Answer 1

If you are using a compiler with c++11 support in it, you can use the to_string method that chris mentioned ( http://www.cplusplus.com/reference/string/to_string/?kw=to_string )

DrawScreenString(1,5, "Lives Remaining: " + std::to_string(livesRemaining), 0xF00000, NULL).

However, if your compiler doesn't have the to_string functionality, you can use a stringstream to construct ( http://www.cplusplus.com/reference/sstream/stringstream/stringstream/ ) or sprintf into a char buffer and then constructing the string from a char buffer. I personally don't like the sprintf option because of the fixed buffer and concerns about overflow of the buffer if the input isn't checked, but it is an option.

Edit: Example with stringstream added per OP request:

#include <sstream>
...
std::stringstream ss;
int livesRemaining = 5;
ss << "Lives remaining: " << livesRemaining;
DrawScreenString(1,5, ss.str(), 0xF00000, NULL);

Answer 2

You can append your string "Lives: " to the livesRemaining variable like so:

"Lives  : %d :"+Integer.toString(uicolor)

OR

"Lives  : %d :"+uicolor + ""

OR

"Lives  : %d :"+String.valueOf(uicolor)

Finally, looking like this for example:

DrawScreenString(10, 5,"Lives  : %d :"+Integer.toString(uicolor), 0xF14040, NULL);
livesRemaining = 3