Function Overloading

Multiple functions can share a name as long as their parameter lists differ. The compiler picks the overload whose parameters best match the arguments:

void print(int i) { std::cout << "int " << i << "\n"; }
void print(double d) { std::cout << "double " << d << "\n"; }
void print(std::string s) { std::cout << "string " << s << "\n"; }

print(1);                   // int 1
print(1.5);                 // double 1.5
print(std::string("hi"));   // string hi

Overloads can differ by the number of parameters or their types:

int add(int a, int b) { return a + b; }
int add(int a, int b, int c) { return a + b + c; }
double add(double a, double b) { return a + b; }

Overloads may have different return types, but the return type alone is not enough to distinguish them:

int add(int a, int b);
double add(int a, int b);  // ERROR: differs only by return type.

void f(int i);
void f(double d);
f('a');  // OK: char promotes to int.
f(1L);   // ERROR: ambiguous, long converts to int and double equally.

Overloads should do the same thing for different types. A reader expects print(int) and print(double) to both print.