I know that std::cout is the C++ equivalent of printf.
What is the C++ equivalent of sprintf?
7 Answers
Example:
#include <iostream>
#include <sstream> // for ostringstream
#include <string>
int main()
{ std::string name = "nemo"; int age = 1000; std::ostringstream out; out << "name: " << name << ", age: " << age; std::cout << out.str() << '\n'; return 0;
}Output:
name: nemo, age: 1000Update, August 2019:
It looks like C++20 will have std::format. The reference implementation is {fmt}. If you are looking for a printf() alternative now, this will become the new "standard" approach and is worth considering.
Original:
Use Boost.Format. It has printf-like syntax, type safety, std::string results, and lots of other nifty stuff. You won't go back.
sprintf works just fine in C++.
2Here's a nice function for a c++ sprintf. Streams can get ugly if you use them too heavily.
std::string string_format(std::string fmt, ...) { int size=100; std::string str; va_list ap; while (1) { str.resize(size); va_start(ap, fmt); int n = vsnprintf(&str[0], size, fmt.c_str(), ap); va_end(ap); if (n > -1 && n < size) { str.resize(n); // Make sure there are no trailing zero char return str; } if (n > -1) size = n + 1; else size *= 2; }
}In C++11 and later, std::string is guaranteed to use contiguous storage that ends with '\0', so it is legal to cast it to char * using &str[0].
You can use iomanip header file to format the output stream. Check this!
1Depending on what exactly you plan on sprintf()ing, std::to_string() might be useful and more idiomatic than other options:
void say(const std::string& message) { // ...
}
int main() { say(std::to_string(5)); say("Which is to say " + std::to_string(5) + " words");
}The main advantage of std::to_string(), IMHO, is that it can be extended easily to support additional types that sprintf() can't even dream of stringifying - kind of like Java's Object.toString() method.
Use a stringstream to achieve the same effect. Also, you can include <cstdio> and still use snprintf.
