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:41:47: warning: 'kthNum' may be used uninitialized in this function [-Wmaybe-uninitialized]
   cout << "The order-" << k << " item is " << kthNum << endl;
                                               ^~~~~~
g++ -g -Wall -O2 -o BubbleSort.o -c BubbleSort.cpp 
g++ -g -Wall -O2 -o InsertSort.o -c InsertSort.cpp 
g++ -g -Wall -O2 -o SelectSort.o -c SelectSort.cpp 
g++ -g -Wall -O2 -o MergeSort.o -c MergeSort.cpp 
g++ -g -Wall -O2 -o QuickSort.o -c QuickSort.cpp 
g++ -g -Wall -O2 -o RSelect.o -c RSelect.cpp 
g++ -g -Wall -O2 -o DSelect.o -c DSelect.cpp 
g++ -g -Wall -O2 -o main main.o BubbleSort.o InsertSort.o SelectSort.o MergeSort.o QuickSort.o RSelect.o DSelect.o
finished

clean (3/3): 
finished

all task finished, build successfully