c++ - TBB parallel_for compile error -

i want use tbb parallel_for had code testing

#include <tbb/parallel_for.h> #include <tbb/blocked_range.h> #include <tbb/tbb.h>  std::vector<std::tuple<std::string, unsigned int, std::string>> commands; auto n = commands.size(); tbb::parallel_for(0, n, [&](int i) {     const auto &tuple = commands[i]; } ); 

my compile line is:

g++ -std=c++11 -wall -wextra -g -og textminingapp.cpp -ltbb -o textminingapp 

and compiler error is:

textminingapp.cpp: in function ‘int main(int, char**)’: textminingapp.cpp:184:7: error: no matching function call ‘parallel_for(int, long unsigned int&, main(int, char**)::<lambda(int)>)’      } );        ^ in file included textminingapp.cpp:15:0: /usr/include/tbb/parallel_for.h:185:6: note: candidate: template<class range, class body> void tbb::parallel_for(const range&, const body&)  void parallel_for( const range&        ^ 

do have idea solve this?

the problem of code 0 of type int, while n of type std::size_t. there's mismatch, , need conversion. solution follows:

tbb::parallel_for(static_cast<std::size_t>(0), n, [&](std::size_t i)) {     // other code     } 

another solution use tbb::blocked_range<t> specify range, i.e. overload tbb::parallel_for.

tbb::parallel_for(tbb::blocked_range<std::size_t>(0, n),     [&](const tbb::blocked_range<std::size_t> &range) {         (auto = range.begin(); != range.end(); ++i)             const auto &tuple = commands[i];     } ); 

obviously, first solution more concise. however, second 1 more flexible. because first one, can specify loop body, while second one, can more outside loop body.