Compilare: main.cpp: In function 'char next_char()': main.cpp:16:32: 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,val,stdin); ^ main.cpp: In function 'int main()': main.cpp:55:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("permutariab.in","r",stdin); ^ main.cpp:56:42: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("permutariab.out","w",stdout); ^