Lab 10 Function Pointer Allows your program to determine which - - PowerPoint PPT Presentation

Lab 10

Allows your program to determine which function to call dynamically.

• Example:

double (*func) (double x); This function pointer signature is to take a double as parameter, and returns a double.

Function Pointer

typedef

Allow you to create alias for a data type, or a function. Example:

• typedef double Currency;
• typedef string FiveString[5];
• typedef double Func(double);

Function Pointer Example

Function Pointer Example

Function Pointer Example

Function Pointer Example

Function Pointer

//existing functions: int function1(){ ... } int function2(int x){ ... } int function3(int x,int y){ ... } int function4(int *x){ ... } //declaring a pointer to function: int (*f1)(); int (*f2)(int); Int (*f3)(int, int); int (*f4)(int *);

#include <iostream> using namespace std; typedef double (*FUNC)(double); double integrate(FUNC f, double a, double b) { // what goes here? } double line(double x){ return x; } double square(double x){ return x*x; } double cube(double x){ return x*x*x; } int main() { cout << "The integral of f(x)=x between 1 and 5 is: " << integrate(line, 1, 5) << endl; // 12 cout << "The integral of f(x)=x^2 between 1 and 5 is: " << integrate(square, 1, 5) << endl; // 41.3333 cout << "The integral of f(x)=x^3 between 1 and 5 is: " << integrate(cube, 1, 5) << endl; // 156 return 0; }

Code outline

In Integration wit ith fu function pointers

f(x) a b

• ffset = 0.001

double integrate(FUNC f, double a, double b){ //f is a pointer to the function of type //double function(double x) //use f(x)*offset to compute the area //of one slice; then sum up all slices. //x is the horizontal position of the //rectangle, and f(x) is the height. return area; }