# deduction guides for `std::stack`

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< cpp‎ | container‎ | stack

Defined in header `<stack>` |  |
template<class Container> stack(Container) -> stack<typename Container::value_type, Container>; | (1) | (since C++17)
template<class Container, class Allocator> stack(Container, Allocator) -> stack<typename Container::value_type, Container>; | (2) | (since C++17)

These deduction guides are provided for stack to allow deduction from underlying container type. This overload only participates in overload resolution if `Alloc` satisfies Allocator, and `Container` does not satisfy Allocator and, for overload (2), if std::uses_allocator_v <Container, Allocator> is `true`

Note: the extent to which the library determines that a type does not satisfy LegacyInputIterator is unspecified, except that as a minimum integral types do not qualify as input iterators. Likewise, the extent to which it determines that a type does not satisfy Allocator is unspecified, except that as a minimum the member type `Alloc::value_type` must exist and the expression std::declval <Alloc&>().allocate( std::size_t {}) must be well-formed when treated as an unevaluated operand.

### Example

Run this code

    #include <vector>
    #include <stack>
    int main() {
       std::vector<int> v = {1,2,3,4};
       std::stack s{v};    // guide #1 deduces std::stack<int, vector<int>>
    }

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