std::deque at() method
- since C++98
// Non const version
reference at( size_type pos );
// Const version
const_reference at( size_type pos ) const;
Returns a reference
to the element at specified indexpos
.
Bounds checking is performed and exception of type std::out_of_range
will be thrown on invalid access, see Exceptions.
Parameters
pos
- position of the element to return
Return value
Reference to the requested element.
Exceptions
Throws std::out_of_range
if pos >= size()
.
Complexity
Constant - O(1).
Example
Main.cpp
#include <iostream>
#include <deque>
int main()
{
std::deque<int> data = { 1, 2, 4, 5, 5, 6 };
// Set element 1
data.at(1) = 88;
// Read element 2
std::cout << "Element at index 2 has value " << data.at(2) << '\n';
std::cout << "data size = " << data.size() << '\n';
try {
// Set element 6
data.at(6) = 666;
} catch (std::out_of_range const& exc) {
std::cout << exc.what() << '\n';
}
// Print final values
std::cout << "data:";
for (int elem : data)
std::cout << " " << elem;
std::cout << '\n';
}
Possible output
Element at index 2 has value 4
data size = 6
deque::_M_range_check: __n (which is 6) >= this->size() (which is 6)
data: 1 88 4 5 5 6
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