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parallel_for Missing ')' Before '{'

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Hello peoples!

So I have what seems (from my point of view) to be a perfectly fine nested group of parallel_fors:

[cpp]parallel_for(primes.begin(), (primes.end()) - 2, 
	{
		if((primes.size()) < 3) return;
		parallel_for(MINEXP, j + 1, [=](int expo)
		{
			i = 3*(primes.front())+3;
			pow((double)i, 1/expo);
			if(!((i%1)<1)) fout << "Sum of " << primes.front() << ":" << (primes.front()) + 3 << " = " << i << "^" << expo << "\n";
		});
	});[/cpp]

Yet, I'm getting all sorts of errors:

[bash]1>------ Build started: Project: primeExp, Configuration: Debug Win32 ------
1>  main.cpp
1>c:\program files\intel\tbb\tbb30_196oss\include\tbb\_tbb_windef.h(60): warning : Recommend using /MD if compiling with TBB_USE_DEBUG==0
1>c:\users\\documents\visual studio 2010\projects\primeexp\primeexp\main.cpp(49): error C2143: syntax error : missing ')' before '{'
1>c:\users\\documents\visual studio 2010\projects\primeexp\primeexp\main.cpp(49): error C2059: syntax error : ')'
1>c:\users\\documents\visual studio 2010\projects\primeexp\primeexp\main.cpp(49): error C2143: syntax error : missing ';' before '{'
1>c:\users\\documents\visual studio 2010\projects\primeexp\primeexp\main.cpp(49): error C2059: syntax error : ')'
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========
 [/bash]
I think the first error is causing the rest. Am I doing something wrong?

Thanks!

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1 Solution
ARCH_R_Intel
Employee
105 Views

A C++0x enabled compiler should reject the code. The problem is the third argument to the outer parallel_for is a brace-deliminted block of code. That's not alowed even in C++0x. I'm guessing that you meant to have a lambda expression there.

Also, the three-argument form of parallel_for expects arguments of integral type for the first two arguments. So either use the initial and one-past-last subscript for the first two arguments, or consider using tbb::parallel_for_each, which acts similarly to std::for_each, but with parallel semantics.

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4 Replies
Kirill_R_Intel
Employee
105 Views

This error appears because C++0x support is not enabled in compiler. In Intel compliler this option is"/Qstd=c++0x" in windows or "-std=c++0x" in Linux.
If you use Visual Studio, go to project properties->C++->Language->Intel specific->Enable C++0x support and set "Yes".

Regards,
Kirill

105 Views
Thanks Kirill! I guess my code is OK then.
ARCH_R_Intel
Employee
106 Views

A C++0x enabled compiler should reject the code. The problem is the third argument to the outer parallel_for is a brace-deliminted block of code. That's not alowed even in C++0x. I'm guessing that you meant to have a lambda expression there.

Also, the three-argument form of parallel_for expects arguments of integral type for the first two arguments. So either use the initial and one-past-last subscript for the first two arguments, or consider using tbb::parallel_for_each, which acts similarly to std::for_each, but with parallel semantics.

View solution in original post

105 Views
It turned out Idid need a lambda in the outer parallel_for for indexing the vector. Thanks everyone!
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