the compiler doesn't seem to accept Agent class

Question

Hey,

probably the answer is quite silly but I need a pair fresh of eyes to spot the problem, if you will. this is the excerpt from _tmain:

Agent theAgent(void);
int m = theAgent.loadSAG();

and this is agent.h, which I included in _tmain:

#ifndef AGENT_H
#define AGENT_H
class Agent {
public:
Agent(void);
int loadSAG(void);
~Agent(void);
};
#endif

and agent.cpp relevant function:

int Agent::loadSAG(void) {
return 3;
}

so why in the world I get this error: error C2228: left of '.loadSAG' must have class/struct/union ?

Thanks in advance.

Answer 1

If by Agent theAgent(void); you meant function declaration then you probably forgot to add () to the function call

int m = theAgent().loadSAG();

If you wanted to define a variable with the name theAgent then you have added extra (void). and instead you should wrote

Agent theAgent;

Answer 2

When calling a default (parameterless) constructor you do so without the '()'. Ie. Try constructing your agent object:

Agent theAgent;

Answer 3

Agent theAgent(void);

This is a function declaration, just change it to:

Agent theAgent;

Answer 4

Compiler thinks

Agent theAgent(void);

This to be a function declaration.

Agent theAgent;

Answer 5

The line

Agent theAgent(void);

Is actually viewed by the compiler as declaring the function theAgent that takes no arguments and returns an Agent.

This is explained the the C++ FAQ Lite.

To call the default constructor and set up an object of type Agent (as opposed to the statement above that's interpreted as a function declaration,) you can just declare theAgent without using parentheses at all, as in:

Agent theAgent;

All normal member calls, such as loadSAG will work as expected after this point.

As an alternative, if you must have the object on the heap, use this instead:

Agent* theAgent = new Agent();  // Notice the *
theAgent->loadSAG();            // Use -> instead of .

// The code where theAgent is used

delete theAgent;  // This frees the memory allocated by new

Answer 6

try

Agent theAgent = new Agent();
theAgent.loadSAG();

The error message looks like you never instantiated an Agent object before you tried to use it.