Compilare: user.cpp: In function ‘bool factor()’: user.cpp:38:33: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (!ok) x=!val[s[j]]; else ^ user.cpp:39:27: warning: array subscript has type ‘char’ [-Wchar-subscripts] x=val[s[j]]; ^ user.cpp: In function ‘int main()’: user.cpp:51:26: warning: array subscript has type ‘char’ [-Wchar-subscripts] scanf("%c",&c); val[c]=1-val[c]; j=1; ^ user.cpp:51:35: warning: array subscript has type ‘char’ [-Wchar-subscripts] scanf("%c",&c); val[c]=1-val[c]; j=1; ^ user.cpp:46:29: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bool.in","r",stdin); ^ user.cpp:47:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("bool.out","w",stdout); ^ user.cpp:48:10: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s+1); n=strlen(s+1); ^ user.cpp:49:17: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&m); ^ user.cpp:51:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c",&c); val[c]=1-val[c]; j=1; ^ user.cpp: In function ‘bool factor()’: user.cpp:43:12: warning: ‘x’ may be used uninitialized in this function [-Wmaybe-uninitialized] return x; ^ /tmp/ccO54I5w.o: In function `main': user.cpp:(.text.startup+0x53): warning: the `gets' function is dangerous and should not be used.