[edit]Parameters

[edit]Return value

true if the elementse of[first, last) arepartitioned with respect to the expressionp(e).false otherwise.

[edit]Complexity

At moststd::distance(first, last) applications ofp.

[edit]Exceptions

The overload with a template parameter namedExecutionPolicy reports errors as follows:

• If execution of a function invoked as part of the algorithm throws an exception andExecutionPolicy is one of thestandard policies,std::terminate is called. For any otherExecutionPolicy, the behavior is implementation-defined.
• If the algorithm fails to allocate memory,std::bad_alloc is thrown.

[edit]Possible implementation

template<class InputIt,class UnaryPred>bool is_partitioned(InputIt first, InputIt last, UnaryPred p){for(; first!= last;++first)if(!p(*first))break;for(; first!= last;++first)if(p(*first))returnfalse;returntrue;}

[edit]Example

#include <algorithm>#include <array>#include <iostream> int main(){std::array<int,9> v{1,2,3,4,5,6,7,8,9}; auto is_even=[](int i){return i%2==0;};std::cout.setf(std::ios_base::boolalpha);std::cout<< std::is_partitioned(v.begin(), v.end(), is_even)<<' '; std::partition(v.begin(), v.end(), is_even);std::cout<< std::is_partitioned(v.begin(), v.end(), is_even)<<' '; std::reverse(v.begin(), v.end());std::cout<< std::is_partitioned(v.cbegin(), v.cend(), is_even)<<' ';std::cout<< std::is_partitioned(v.crbegin(), v.crend(), is_even)<<'\n';}

false true false true

[edit]See also

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