View Compilation Error

0_0_8292515_15814.cpp: In function `int main()':
0_0_8292515_15814.cpp:31: error: `scanf' undeclared (first use this function)
0_0_8292515_15814.cpp:31: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_8292515_15814.cpp:31: error: `EOF' undeclared (first use this function)
0_0_8292515_15814.cpp:47: error: `qsort' undeclared (first use this function)
0_0_8292515_15814.cpp:54: error: `printf' undeclared (first use this function)