Compilare: main.cpp: In function 'int main()': main.cpp:28:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("difprim.in","r",stdin); ^ main.cpp:29:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("difprim.out","w",stdout); ^ main.cpp:31:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&a,&b); ^ main.cpp:63:20: warning: 'p2' may be used uninitialized in this function [-Wmaybe-uninitialized] for(int i = p2+2 ; i <= b ; i+=2) ^ main.cpp:52:11: warning: 'p1' may be used uninitialized in this function [-Wmaybe-uninitialized] x = p1+2; ~~^~~~~~