prepare (1/3): 
finished

make (2/3): 
g++ -g -Wall -O2 -o main.o -c main.cpp 
main.cpp: In function 'int main()':
main.cpp:29:55: warning: 'result' may be used uninitialized in this function [-Wmaybe-uninitialized]
     cout << "The order-" << order_i << " item is " << result << endl;
                                                       ^~~~~~
g++ -g -Wall -O2 -o selection.o -c selection.cpp 
selection.cpp: In function 'int in_place_partition_determine(int*, int, int, int)':
selection.cpp:103:9: warning: 'pivotrand' may be used uninitialized in this function [-Wmaybe-uninitialized]
     int pivotrand;
         ^~~~~~~~~
g++ -g -Wall -O2 -o main main.o selection.o
finished

clean (3/3): 
finished

all task finished, build successfully