Compilare: main.cpp: In function 'int main()': main.cpp:84:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("trapezoid.in", "r", stdin); ^ main.cpp:85:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("trapezoid.out", "w", stdout); ^ main.cpp: In function 'char nextch()': main.cpp:68:30: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buff, 1, BMAX, stdin); ^