openmp lastprivate
时间: 2024-04-29 09:25:23 浏览: 18
The lastprivate clause in OpenMP is used to ensure that the last value of a private variable is retained after the parallel region ends. This clause is used to declare a variable as being both private and lastprivate.
The last value of the private variable is copied back to the original variable outside the parallel region. This ensures that the final value of the variable is available for further use in the program.
For example, consider the following code:
```
#include <stdio.h>
#include <omp.h>
int main() {
int i, sum = 0;
#pragma omp parallel for lastprivate(i)
for (i = 0; i < 10; i++) {
sum += i;
}
printf("Total sum is %d\n", sum);
printf("Last value of i is %d\n", i);
return 0;
}
```
In this code, the lastprivate clause is used to declare the variable i as being both private and lastprivate. This means that each thread has its own copy of i, but the last value of i is copied back to the original variable outside the parallel region.
When the program is run, the output will be:
```
Total sum is 45
Last value of i is 10
```
This shows that the final value of i is retained after the parallel region ends, and can be used for further computation if needed.
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