Compilare: user.cpp: In function ‘void valid(char*)’: user.cpp:7:10: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=1;i<=strlen(v);i++) ^ user.cpp:8:8: warning: array subscript has type ‘char’ [-Wchar-subscripts] {if(v[i]=='(') nr++; ^ user.cpp:9:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] else if(v[i]==')') nr--; ^ user.cpp:10:12: warning: array subscript has type ‘char’ [-Wchar-subscripts] else if(v[i]>='9'||v[i]!='*'||v[i]!='+'||v[i]!='-'||v[i]!='/')ok=0; ^ user.cpp:10:23: warning: array subscript has type ‘char’ [-Wchar-subscripts] else if(v[i]>='9'||v[i]!='*'||v[i]!='+'||v[i]!='-'||v[i]!='/')ok=0; ^ user.cpp:10:34: warning: array subscript has type ‘char’ [-Wchar-subscripts] else if(v[i]>='9'||v[i]!='*'||v[i]!='+'||v[i]!='-'||v[i]!='/')ok=0; ^ user.cpp:10:45: warning: array subscript has type ‘char’ [-Wchar-subscripts] else if(v[i]>='9'||v[i]!='*'||v[i]!='+'||v[i]!='-'||v[i]!='/')ok=0; ^ user.cpp:10:56: warning: array subscript has type ‘char’ [-Wchar-subscripts] else if(v[i]>='9'||v[i]!='*'||v[i]!='+'||v[i]!='-'||v[i]!='/')ok=0; ^ user.cpp: In function ‘int main()’: user.cpp:19:7: warning: unused variable ‘r’ [-Wunused-variable] {char r; ^