Array of pointer-to-functions

[Juha Nieminen]

You conveniently omitted the context, was "declare where used".

Perhaps you missed my point.

 

[Luca Risolia]

You must be joking.

You conveniently omitted the context, was "declare where used".

$ g++ -o /tmp/bbb /tmp/a.cpp
/tmp/a.cpp: In function 'int main(int, char**)':
/tmp/a.cpp:27:1: error: jump to label 'leave' [-fpermissive]
/tmp/a.cpp:19:12: error: from here [-fpermissive]
/tmp/a.cpp:23:7: error: crosses initialization of 'int b'

There is no need of goto in your example to release the lock, hence
there is no need to define variables "at the beginning of the block"
(far from where they are used) to avoid the cross initialization. Using
the RAII idiom makes programs less error-prone, shorter and let you
initialize variables where they are used:

pthread_mutex_t lock;

int
main(int arg, char **argv)
{
int a = strtoul(argv[1], NULL, 0);

pthread_mutex_init(&lock, NULL);

struct Lock {
Lock() noexcept { pthread_mutex_lock(&lock); }
~Lock() { pthread_mutex_unlock(&lock); }
} lock;

a = a + 1;
if (a == 3)
return EXIT_SUCCESS;
a = a + 3;

int b = a;

printf("%d\n", b);

return EXIT_SUCCESS;
}

 

[I]

You already have an index into the array (or vector). There is no need for a switch. The switch is redundant. See below: for(int i=0;i<size_choice;i++) { cin>>choice; // Choice is already an index into the // array of function pointers... Get it? (*array_of_pointers[choice])(...); }

Ahh yep. Thanks.

 

[Ian Collins]

You must be joking.

You conveniently omitted the context, was "declare where used".

$ g++ -o /tmp/bbb /tmp/a.cpp
/tmp/a.cpp: In function 'int main(int, char**)':
/tmp/a.cpp:27:1: error: jump to label 'leave' [-fpermissive]
/tmp/a.cpp:19:12: error: from here [-fpermissive]
/tmp/a.cpp:23:7: error: crosses initialization of 'int b'

Those are a consequence of writing spaghetti code rather than
initialising a variable where it is used! It's good to see compilers
issuing such errors.