Read in C++

To read a file in C++, you can use the std::ifstream class provided in the header file. Here is an example code that demonstrates how to open a file and read its contents using a while loop:

``c++
#include
#include
#include

int main() {
std::ifstream file("example.txt");
std::string line;

if (file.is_open()) { // check if the file opened successfully
while (std::getline(file, line)) { // read each line in the file
std::cout << line << '\n'; // output the line to the console
}
file.close(); // close the file when finished
}
else {
std::cout << "Unable to open file\n";
}
return 0;
}
`

In this code, we first create an std::ifstream object called file, which we use to open the file "example.txt". We also create an std::string called line which will be used to store each line of the file as we read it.

Next, we check whether the file was opened successfully using the is_open() method provided by the std::ifstream class. If it was, we enter a loop that reads each line of the file using the std::getline() function. This function takes two arguments: the std::ifstream object we created (file), and the std::string object we created to store each line (line). It reads each line of the file until the end of the file is reached.

Finally, we output each line to the console using std::cout, and close the file using the close()` method before returning 0 to indicate success. If the file could not be opened, we simply output an error message to the console.