"18.2.2. Function Pointers\n\nFunctions are just pieces of code that reside somewhere in memory just as variables do. Since we can create pointers that point to variables, it makes sense to be able to create variables that point to functions too! These are referred to as function pointers. The syntax for declaring function pointers is similar to variable pointers. However, since a function’s signature involves a return type and parameter list, these need to be specified. For example, suppose we wanted to create a function pointer that could point to the math library’s sqrt() function which takes a single double parameter and returns a double value.\n\ndouble (*ptrToSqrt)(double) = NULL;\n\nThe above line creates a function pointer that can point to any function that takes a single double parameter and returns a double value. As is good practice, we’ve initialized it to point to NULL. The function pointer itself is named ptrToSqrt. To make it point to the sqrt() function we can use the following syntax.\n\nptrToSqrt = sqrt;\n\nThis is because a function’s identifier acts as a pointer as well! Once we have a pointer to a function, we can invoke the function via its pointer as we would any other function call."