C++ create string of text and variables

Question

I\'m trying to do something very simple and yet, after an hour of so of searching a I can\'t find a suitable answer so I must be missing something fairly obvious.

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Answer 1

std::string var = "sometext" + somevar + "sometext" + somevar;

This doesn't work because the additions are performed left-to-right and "sometext" (the first one) is just a const char *. It has no operator+ to call. The simplest fix is this:

std::string var = std::string("sometext") + somevar + "sometext" + somevar;

Now, the first parameter in the left-to-right list of + operations is a std::string, which has an operator+(const char *). That operator produces a string, which makes the rest of the chain work.

You can also make all the operations be on var, which is a std::string and so has all the necessary operators:

var = "sometext";
var += somevar;
var += "sometext";
var += somevar;

Answer 2

Have you considered using stringstreams?

#include <string>
#include <sstream>

std::ostringstream oss;
oss << "sometext" << somevar << "sometext" << somevar;
std::string var = oss.str();

Answer 3

The new way to do with c++20 is using format.

#include <format>

auto var = std::format("sometext {} sometext {}", somevar, somevar);

Answer 4

In C++11 you can use std::to_string:

std::string var = "sometext" + std::to_string(somevar) + "sometext" + std::to_string(somevar);  

Answer 5

You can also use sprintf:

char str[1024];
sprintf(str, "somtext %s sometext %s", somevar, somevar);

Answer 6

See also boost::format:

#include <boost/format.hpp>

std::string var = (boost::format("somtext %s sometext %s") % somevar % somevar).str();