References in C++

A reference is another name for an existing variable — safer and cleaner than a pointer for passing arguments.

Easy

void scale(double &value, double gain) { value *= gain; }

double v = 2.0;
scale(v, 3.0);         // v is now 6.0

void print(const std::string &s);   // pass large objects by const reference: no copy

A reference must be initialised, can't be null and can't be re-bound to another variable. Use const T& for read-only parameters, T& when the function must modify the argument.

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