View Compilation Error

0_0_21401924_30673.cpp: In function 'int main()':
0_0_21401924_30673.cpp:43:32: error: variable 'std::istringstream i' has initializer but incomplete type
             istringstream i(str);
                                ^
0_0_21401924_30673.cpp:62:32: error: variable 'std::istringstream i' has initializer but incomplete type
             istringstream i(str);
                                ^