View Compilation Error

0_0_12157325_8938.cpp: In function `int rect_comp_by_area(const rect*, const rect*)':
0_0_12157325_8938.cpp:25: error: invalid conversion from `const rect*' to `rect*'
0_0_12157325_8938.cpp:26: error: invalid conversion from `const rect*' to `rect*'
0_0_12157325_8938.cpp: In function `int main(int, char**)':
0_0_12157325_8938.cpp:46: error: invalid conversion from `int (*)(const rect*, const rect*)' to `int (*)(const void*, const void*)'
0_0_12157325_8938.cpp:46: error:   initializing argument 4 of `void qsort(void*, size_t, size_t, int (*)(const void*, const void*))'