Create a C++ string with given format

Question

I'm a Objective-C dev and sometimes I have to deal with C/C++ code. I have a function written in C++, it logs an event with name, for example, Level_12_Pack_10. I want to create a dynamic C++ string like that, then I can change level and pack numbers. In Objective C, it's easy with some lines of code: [NSString stringwithformat] but in C++, it's a bit difficult for me. Could anyone help me do it?

What you want is easy enough. Show us what you have tried. Look up std::string in the stl. You might look for examples of ostream operator<< overloading. — ChuckCottrill
– ChuckCottrill, Commented Oct 29, 2013 at 3:13

Zach Stark · Accepted Answer · 2013-10-29 03:15:26Z

1

I don't think C++ supports strings with built-in changeable variables like that. It would be too over-the-top to make a class to format the string like that. Probably the closest thing you can get is to use stringstreams:

#include <sstream>
string makeMyString(int level, int pack) {
  stringstream ss;
  ss << "Level_" << level << "_Pack_" << pack;
  return ss.str();
}

If you have a string that you need to read and change the values inside, a similar function could be used.

answered Oct 29, 2013 at 3:15

Zach Stark

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Stocptimal · Accepted Answer · 2013-10-29 04:25:52Z

1

With c++11, it is drop dead simple just use std::to_string(level) etc to concatenate strings.

int level = 10;
int pack = 40;

std::string stuff = "Level_" + std::to_string(level) + "_Pack_" + std::to_string(pack);
//stuff is now "Level_10_Pack_40"
std::cout << stuff;

answered Oct 29, 2013 at 4:25

Stocptimal

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