Listing 5: Sample use of expression evaluator

C_Like_Expression  c2("1  +  3  ==  8/2  &&  0");
cout  <<  c2.GetExp()  <<  "  =>  "    <<  c2.GetValue()<<  endl  <<  endl;

Pascal_Like_Expression  p2("1  +  3  =  8/2  and  0");
cout  <<  p2.GetExp()  <<  "  =>  "    <<  p2.GetValue()<<  endl  <<  endl;

Symbol_Table  sym;
sym.Set("v1",5);  sym.Set("v2",9);  sym.Set("v3",32);
sym.Set("Temperature",50);

C_Like_Expression  c3("Temperature*v1/v2+v3");
cout  <<  c3.GetExp()  <<  "  =>  "    <<  c3.GetValue(sym)<<  endl  <<  endl;

C_Like_Expression  c4("1  &&  (1==v1  ||  !(4-1-2-1))");
cout  <<  c4.GetExp()  <<  "  =>  "    <<  c4.GetValue(sym)<<  endl  <<  endl;

sym.Set("TRUE",1);
Pascal_Like_Expression  p4("TRUE  and  (1=v1  or  not(4-1-2-1))");
cout  <<  p4.GetExp()  <<  "  =>  "    <<  p4.GetValue(sym)<<  endl  <<  endl;

//End of File

Output:

3.  1  +  3  ==  8/2  &&  0  =>  0

4.  1  +  3  =  8/2  and  0  =>  0

Temperature*v1/v2+v3  =>  59.7778

1  &&  (1==v1  ||  !(4-1-2-1))  =>  1

TRUE  AND  (1=v1  or  NOT(4-1-2-1))  =>  1