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OOP344-Jason Quan C/C++ Programs & notes-20102

1,688 bytes added, 22:34, 4 June 2010
added first notes to my notes page
==pointer to functions==
A pointer can be used to point to anything. Therefore you can also use it to point to a function, here’s an simple c program that uses pointer to function:

void windows(char,int);
void mac(char,int);
int main(void) {
void (*platform)(char,int); /* this a declaration of a function pointer with
a argument of char and int*/
char name[30];
int option;
printf("Please enter your name: ");
scanf("%s", &name);
printf("Which platform 1.Windows, 2.Mac:");
scanf("%d", &option);
platform = (option < 2) ? windows : mac; /* this line assign where the
platform pointer should point to.*/
(option > 2||option<1) && printf("error: pick 1 or 2\n"); /*Lazy Evaculation*/
platform(name , option);

return 0;
void windows(char* str,int n) {
printf("%s you've choosen option %d, you are a Windows user.\n",str,n);
void mac(char* str,int m) {
printf(" %s you've chosen Option %d, you are Mac user.\n",str, m);

In this program two functions are declared: void Windows(char *str,int n) and void Mac(char *str ,int m) they both return void. But the output a line. Within the main() a void pointer call platform is declared with two arugments( char, int) which are values types that will be pasted to the corrsponding functions which is determine by this line :
platform = (option < 2) ? windows : mac;

<p>If the user chooses option 1 platform will be set to point to the windows function else Mac fun ction otherwise. To call the function, you would call it using the pointer platform by use a line:
platform(name , option);
this line will call the function.</p>

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