Compilare: user.cpp: In function ‘int val(int, int)’: user.cpp:30:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(pz1<X.size()) ^ user.cpp:33:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=pz1+1;i<X.size()&&(smn[i-1]=='*'||smn[i-1]=='/');i++) ^ /tmp/ccIctcIo.o: In function `main': user.cpp:(.text.startup+0x4e): warning: the `gets' function is dangerous and should not be used.