For the sake of completeness, you may use std::stringstream:
#include <iostream>
#include <sstream>
#include <string>
int main() {
std::string a = "a", b = "b", c = "c";
// apply formatting
std::stringstream s;
s << a << " " << b << " > " << c;
// assign to std::string
std::string str = s.str();
std::cout << str << "\n";
}
Or (in this case) std::string's very own string concatenation capabilities:
#include <iostream>
#include <string>
int main() {
std::string a = "a", b = "b", c = "c";
std::string str = a + " " + b + " > " + c;
std::cout << str << "\n";
}
For reference:
If you really want to go the C way. Here you are:
#include <iostream>
#include <string>
#include <vector>
#include <cstdio>
int main() {
std::string a = "a", b = "b", c = "c";
const char fmt[] = "%s %s > %s";
// use std::vector for memory management (to avoid memory leaks)
std::vector<char>::size_type size = 256;
std::vector<char> buf;
do {
// use snprintf instead of sprintf (to avoid buffer overflows)
// snprintf returns the required size (without terminating null)
// if buffer is too small initially: loop should run at most twice
buf.resize(size+1);
size = std::snprintf(
&buf[0], buf.size(),
fmt, a.c_str(), b.c_str(), c.c_str());
} while (size+1 > buf.size());
// assign to std::string
std::string str(buf.begin(), buf.begin()+size);
std::cout << str << "\n";
}
For reference:
Then, there's the Boost Format Library. For the sake of your example:
#include <iostream>
#include <string>
#include <boost/format.hpp>
int main() {
std::string a = "a", b = "b", c = "c";
// apply format
boost::format fmt = boost::format("%s %s > %s") % a % b % c;
// assign to std::string
std::string str = fmt.str();
std::cout << str << "\n";
}