Q: Since array references decay into pointers, if arr is an array, what's the difference between arr and &arr?
A: The type.
In Standard C, &arr yields a pointer, of type pointer-to-array-of-T, to the entire array. (In pre-ANSI C, the & in &arr generally elicited a warning, and was generally ignored.) Under all C compilers, a simple reference (without an explicit &) to an array yields a pointer, of type pointer-to-T, to the array's first element.
For a simple array
int a;a reference to a has type ``pointer to int,'' and &a is ``pointer to array of 10 ints.'' For a two-dimensional array like
int array[NROWS][NCOLUMNS];a reference to array has type ``pointer to array of NCOLUMNS ints,'' while &array has type ``pointer to array of NROWS arrays of NCOLUMNS ints.''
See also questions 6.3, 6.13, and 6.18.
ISO Sec. 18.104.22.168, Sec. 22.214.171.124
Rationale Sec. 126.96.36.199
H&S Sec. 7.5.6 p. 198