c++ transform with pair get Segmentation fault
c++, std-pair, stl, transform
Solution
That is because `transform` is expecting `results` object to have the required memory allocated i.e. it is expecting `results.size()` is atleast as big as `tests.size()`. If you want to push_back operation to be performed on the `results` then you should use `std::back_inserter(results)` as the third argument. Otherwise, when `transform` uses the `*` output iterator you passed, it will be a invalid memory location and will result in a segmentation fault.
Problem
This code works: ``` class Test { public: Test(string name) : _name(name) {}; bool operator()() { cout << "hello " << _name << endl; return true; } string name() { return _name; } private: string _name; }; pair<string, bool> inline execute_test(Test* t) { return pair<string, bool>(t->name(), (*t)()); } int main() { vector<Test*> tests; vector<pair<string, bool> > results; tests.push_back(new Test("Test1")); tests.push_back(new Test("Test2")); for (unsigned int i=0; i < tests.size(); ++i) results.push_back(execute_test(tests[i])); } ``` now I want to use trasform instead of the for cicle: ``` transform(tests.begin(), tests.end(), results.begin(), execute_test); ``` but I got a Segmentation Fault. Where is the problem?