array size?

[mart_man00]

how can you figure out the size allocated for a array, how much can safely be put in it?

i mean i do something like

char temp[255];
strcpy(temp, "test");
printf("Array temp is %i chars long", strlen(temp));

gives 4, but its really 255(well, 254), how can i get 255?

testing for a seg fault just seems horible.

[Polymorphic OOP]

sizeof( temp )

[mart_man00]

so can it be done if the size isnt known(not compiled with that particular size)?

[Polymorphic OOP]

Originally posted by Salem
> sizeof( temp )
Beware that this only works when the array itself is in scope.

Pass the array to a function and all you will ever get is the size of the pointer to the start of the array

Only if you are passing the the address of the first element. If you pass the address of the array, you can still use sizeof to get the proper size (you'd do sizeof( *temp ) ).

so can it be done if the size isnt known(not compiled with that particular size)?

you mean, for instance, if you dynamically allocated it? Nope, there is no standard way in C to get the size of the array. You'd have to just store the size to a variable when you allocate it.

[Polymorphic OOP]

Originally posted by Salem
What are you on about poly?

void fn2 ( char (*a)[10] ) {
    printf( "%d\n", sizeof(a) );
    printf( "%d\n\n", sizeof(*a) );
}

^ was what I was refering too.


I know it's silly because, of course, you can only pass arrays of length 10 to it. The only reason I mentioned it was because his original example was also silly. He showed the declaration meaning he knew the size at compile-time, just like the above example.