◆ replace_if() [1/4]

template<typename DerivedPolicy , typename ForwardIterator , typename Predicate , typename T >
__host__ __device__ void thrust::replace_if ( const thrust::detail::execution_policy_base< DerivedPolicy > &  exec,
ForwardIterator  first,
ForwardIterator  last,
Predicate  pred,
const T &  new_value 

replace_if replaces every element in the range [first, last) for which pred returns true with new_value. That is: for every iterator i, if pred(*i) is true then it performs the assignment *i = new_value.

The algorithm's execution is parallelized as determined by exec.

execThe execution policy to use for parallelization.
firstThe beginning of the sequence of interest.
lastThe end of the sequence of interest.
predThe predicate to test on every value of the range [first,last).
new_valueThe new value to replace elements which pred(*i) evaluates to true.
Template Parameters
DerivedPolicyThe name of the derived execution policy.
ForwardIteratoris a model of Forward Iterator, ForwardIterator is mutable, and ForwardIterator's value_type is convertible to Predicate's argument_type.
Predicateis a model of Predicate.
Tis a model of Assignable, and T is convertible to ForwardIterator's value_type.

The following code snippet demonstrates how to use replace_if to replace a device_vector's negative elements with 0 using the thrust::device execution policy for parallelization:

#include <thrust/replace.h>
struct is_less_than_zero
__host__ __device__
bool operator()(int x)
return x < 0;
thrust::device_vector<int> A(4);
A[0] = 1;
A[1] = -3;
A[2] = 2;
A[3] = -1;
is_less_than_zero pred;
thrust::replace_if(thrust::device, A.begin(), A.end(), pred, 0);
// A contains [1, 0, 2, 0]
See also