Compilare: user.cpp: In function ‘void eval()’: user.cpp:40:16: warning: NULL used in arithmetic [-Wpointer-arith] while (*p!=NULL){ ^ user.cpp: In function ‘int main()’: user.cpp:57:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("expresie2.in", "r", stdin); ^ user.cpp:58:42: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("expresie2.out", "w", stdout); ^ user.cpp:60:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(c); ^ /tmp/ccNDqll4.o: In function `main': user.cpp:(.text.startup+0x54): warning: the `gets' function is dangerous and should not be used.