The problem is that row
is an int *
and not a int[4]
as one would expect because arrays decay to pointers and there is no automatic way to know how many elements a pointer points to.
To get around that problem std::array
has been added where everything works as expected:
#include <array>
int main() {
std::array<std::array<int, 4>, 3> ia;
for (auto &row : ia){
for (auto &col : row){
col = 0;
}
}
}
Note the &
before row
and col
which indicate that you want a reference and not a copy of the rows and columns, otherwise setting col
to 0 would have no effect on ia
.
To prevent the decay of the int[]
to int*
you can use &&
int main() {
int ia[3][4];
for (auto && row : ia)
for (auto && col : row)
;
}
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