View Compilation Error

0_0_10191807_23923.cpp: In function `int cmp(const void*, const void*)':
0_0_10191807_23923.cpp:38: error: `aa' undeclared (first use this function)
0_0_10191807_23923.cpp:38: error: (Each undeclared identifier is reported only once for each function it appears in.)
0_0_10191807_23923.cpp:38: error: `bb' undeclared (first use this function)