Compilare: user.cpp: In function ‘int main()’: user.cpp:21:19: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] E[strlen(E)-1]=NULL; ^ user.cpp:30:19: warning: NULL used in arithmetic [-Wpointer-arith] for(i=0;E[i]!=NULL;i++) ^ user.cpp:51:21: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] sirnr[k]=NULL; ^ user.cpp:67:24: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] aux[2]=NULL; ^ user.cpp:87:30: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] aux[2]=NULL; ^ user.cpp:103:43: warning: NULL used in arithmetic [-Wpointer-arith] if(*p=='+' || (*p=='-' && *(p+1)==NULL) ||*p=='*' || *p=='/') ^ user.cpp: In function ‘int prioritate(char)’: user.cpp:11:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:19:22: warning: ignoring return value of ‘char* fgets(char*, int, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fgets(E,100000,f); ^