i'm using c to write program for microchip microcontroller.

recently i come across with one program from internet which i confuse with one of the code

normally for array in c, i just write
bitmap[]={5,5,5};
temp=bitmap[0]-1; then i get temp=4;

but now i saw from the code, it's written there
temp1=bitmap;
temp2=bitmap-1;

may i know what's mean by bitmap-1?(just the array name)

i try to run some simple simulation for the code, i get the answer
temp1=10;
temp2=9;

but i don't understand where its value come from.

thanks.

 

I'm guessing it's using pointers, but without seeing the rest of the code and specifically the variable declarations, it is only a guess..

 

It is indeed using pointers. The name of any array is in fact a pointer to the first element of that array if you have an array test[];
then a = test[0]; and a = test; will produce the same result.

 

The syntax and semantics came from the original K&R. Specifically, an array name, foo, was to be interpreted as:

&foo[0]

or in other words the address of the first element in the array.

 

Yes, but it cannot be the array name -1, that would be one element below the start of the array.

It would only make sense with a pointer used within the array.

 

Depends on the presence or absence of array bounds checking. In the freewheeling early days it was unlikely to be there. Such things can very occasionally be useful but more often than not are a source of great pain and frustration. Evaluating such an expression is probably benign; deferencing is probably not benign

 

thanks a lot to all of your reply.
yup, the result is represent address of the pointer 1st array..i check it on FileRegister and get the answer.

Thanks