C Tutorial/Function/Function Pointer
Содержание
Arrays of Pointers to functions
<source lang="cpp">#include <stdio.h> int sum(int x, int y){
return x + y;
} int product(int x, int y){
return x * y;
} int difference(int x, int y){
return x - y;
} int main(void){
int a = 10;
int b = 5;
int result = 0;
int (*pfun[3])(int, int); /* Function pointer array declaration */
/* Initialize pointers */
pfun[0] = sum;
pfun[1] = product;
pfun[2] = difference;
int i;
for(i = 0 ; i < 3 ; i++)
{
result = pfun[i](a, b); /* Call the function through a pointer */
printf("\nresult = %d", result); /* Display the result */
}
return 0;
}</source>
result = 15
result = 50
result = 5
Passing a pointer of a function to another function
<source lang="cpp">/* Beginning C: From Novice to Professional, Fourth Edition By Ivor Horton ISBN: 1-59059-735-4 640 pp. Published: Oct 2006
- /
- include <stdio.h>
int any_function(int(*pfun)(int, int), int x, int y){
return pfun(x, y);
} int sum(int x, int y){
return x + y;
} int product(int x, int y){
return x * y;
} int difference(int x, int y){
return x - y;
} int main(void){
int a = 10;
int b = 5;
int result = 0;
int (*pf)(int, int) = sum; /* Pointer to sum function */
result = any_function(pf, a, b);
printf("\nresult = %d", result );
result = any_function(product,a, b);
printf("\nresult = %d", result );
printf("\nresult = %d\n", any_function(difference, a, b));
return 0;
}</source>
result = 15
result = 50
result = 5
Pointing to functions
<source lang="cpp">#include <stdio.h> int sum(int x, int y) {
return x + y;
}
int product(int x, int y) {
return x * y;
}
int difference(int x, int y) {
return x - y;
}
int main(void) {
int a = 10;
int b = 5;
int result = 0;
int (*pfun)(int, int); /* Function pointer declaration */
pfun = sum;
result = pfun(a, b); /* Call sum() through pointer */
printf("\npfun = sum result = %d", result);
pfun = product;
result = pfun(a, b); /* Call product() through pointer */
printf("\npfun = product result = %d", result);
pfun = difference;
result = pfun(a, b); /* Call difference() through pointer */
printf("\npfun = difference result = %d\n", result);
return 0;
}</source>
pfun = sum result = 15
pfun = product result = 50
pfun = difference result = 5
Using array of pointers to functions in one statement
<source lang="cpp">#include <stdio.h> int sum(int x, int y){
return x + y;
} int product(int x, int y){
return x * y;
} int difference(int x, int y){
return x - y;
} int main(void){
int a = 10;
int b = 5;
int result = 0;
int (*pfun[3])(int, int); /* Function pointer array declaration */
/* Initialize pointers */
pfun[0] = sum;
pfun[1] = product;
pfun[2] = difference;
/* Call all three functions through pointers in an expression */
result = pfun[1](pfun[0](a, b), pfun[2](a, b));
printf("\n\nThe product of the sum and the difference = %d\n",
result);
return 0;
}</source>
The product of the sum and the difference = 75
