View Compilation Error

0_0_10084527_21963.cpp: In function `int main()':
0_0_10084527_21963.cpp:22: error: `qsort' undeclared (first use this function)
0_0_10084527_21963.cpp:22: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_10084527_21963.cpp:25: error: `abs' undeclared (first use this function)