View Compilation Error

0_0_1236030_10640.cpp: In function `double kruskal(int, int, EdgeNode*, EdgeNode*)':
0_0_1236030_10640.cpp:66: error: `qsort' undeclared (first use this function)
0_0_1236030_10640.cpp:66: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_1236030_10640.cpp:67: error: `memset' undeclared (first use this function)
0_0_1236030_10640.cpp:75: error: `memcpy' undeclared (first use this function)
0_0_1236030_10640.cpp: In function `int main()':
0_0_1236030_10640.cpp:100: error: `memset' undeclared (first use this function)