Compilare: user.cpp: In function ‘int main()’: user.cpp:20:25: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in,"%d\n",&Q); ^ user.cpp:25:26: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(s1,Nmax,in); ^ user.cpp:26:26: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(s2,Nmax,in); ^ user.cpp: In function ‘bool neg_f(char*)’: user.cpp:91:23: warning: ‘val’ may be used uninitialized in this function [-Wmaybe-uninitialized] val=val==0?1:0; ^