Comparing arrays for equality in C++
You're not comparing the contents of the arrays, you're comparing the addresses of the arrays. Since they're two separate arrays, they have different addresses.
Avoid this problem by using higher-level containers, such as std::vector
, std::deque
, or std::array
.
Since nobody mentioned it yet, you can compare arrays with the std::equal
algorithm:
int iar1[] = {1,2,3,4,5};
int iar2[] = {1,2,3,4,5};
if (std::equal(std::begin(iar1), std::end(iar1), std::begin(iar2)))
cout << "Arrays are equal.";
else
cout << "Arrays are not equal.";
You need to include <algorithm>
and <iterator>
. If you don't use C++11 yet, you can write:
if (std::equal(iar1, iar1 + sizeof iar1 / sizeof *iar1, iar2))
if (iar1 == iar2)
Here iar1
and iar2
are decaying to pointers to the first elements of the respective arrays. Since they are two distinct arrays, the pointer values are, of course, different and your comparison tests not equal.
To do an element-wise comparison, you must either write a loop; or use std::array
instead
std::array<int, 5> iar1 {1,2,3,4,5};
std::array<int, 5> iar2 {1,2,3,4,5};
if( iar1 == iar2 ) {
// arrays contents are the same
} else {
// not the same
}
Array is not a primitive type, and the arrays belong to different addresses in the C++ memory.