Question

C++

Modify FunctionTable.cpp so each that each function returns a string(instead of printing out a message) and so that this value is printed inside of main().

//: C03:FunctionTable.cpp
// Using an array of pointers to functions
#include <iostream>
using namespace std;
// A macro to define dummy functions:
#define DF(N) void N() { \
cout << "function " #N " called..." << endl; }
DF(a); DF(b); DF(c); DF(d); DF(e); DF(f); DF(g);
void (*func_table[])() = { a, b, c, d, e, f, g };
int main() {
while(1) {
cout << "press a key from 'a' to 'g' "
"or q to quit" << endl;
char c, cr;
cin.get(c); cin.get(cr); // second one for CR
if ( c == 'q' )
break; // ... out of while(1)
if ( c < 'a' || c > 'g' )
continue;
(*func_table[c - 'a'])();
}
}

Answer 1

#include <iostream>
using namespace std;
// A macro to define dummy functions:
//#define DF(N) void N() { \
cout << "function " #N " called..." << endl; }
//DF(a); DF(b); DF(c); DF(d); DF(e); DF(f); DF(g);

string DF(char s)
{
   if(s=='a')
   return(" A is called");
   if(s=='b')
   return(" B is called");
   if(s=='c')
   return(" C is called");
   if(s=='d')
   return(" D is called");
   if(s=='e')
   return(" E is called");
   if(s=='f')
   return(" F is called");
   if(s=='g')
   return(" G is called");

  
}

//void (*func_table[])() = { a, b, c, d, e, f, g };

int main()
{
while(1)
{
   
cout << "press a key from 'a' to 'g' "
"or q to quit" << endl;

char c, cr;
string ss;

cin.get(c); cin.get(cr); // second one for CR

if ( c == 'q' )
break; // ... out of while(1)

if ( c < 'a' || c > 'g' )
continue;

cout<<DF(c)<<endl;
//(*func_table[c - 'a'])();

}
}