Beispiel für functionpointer in c

c_function_pointer.c

#include <stdio.h>
#include <math.h>

double f1(double x) {return x*x*x;}

double xq(double x) {return x*x;}

double sin_func(double x) {return sin(x);}

double f(double begin, double end, double pieces, double (*fp)(double)) 
{
        double delta_x = (end-begin)/pieces;
        //printf("delta_x = %f\n", delta_x);    
        int i;
        double return_value = 0;
        for(i=0;i<=pieces;i++) {
                return_value += fp(begin+(i*delta_x)+(delta_x*0.5))*delta_x;
        }
        return return_value;
}


int main( int argc, char **argv)
{
        //int i = 0;
        //double result = f(0,2,100);
        //double (fp*)(double);

        printf("Result [0,2]: %f\n", f(0,2,100, xq));
        printf("Result [1,2]: %f\n", f(1,2,100, xq));   
        printf("Result [-1,1]: %f\n", f(-1,1,100, xq));
        printf("Result [4,7]: %f\n", f(4,7,100, xq));
        printf("Result [0,2] 20rec: %f\n", f(0,2,20, xq));
        printf("Result [0,2] 60rec: %f\n", f(0,2,60, xq));
        printf("Result [0,2] 200rec x^3: %f\n", f(0,2,200, f1));
        printf("Result [0,PI] 200rec: %f\n", f(0,M_PI,20, sin_func));
        
return 0;
}