What do these errors mean?

[Julianne]

This code is from a slide my teacher posted for us in class, but he took it down before I could double check to make sure I typed it all in right. I have the following errors below..Can someone tell me what they mean and how to fix this? Thanks..

Errors:
[linker error] undefined reference to 'squareByValue(int)'
[linker error] undefined reference to 'squarebyReference(int&)'
Id returned 1 exit status

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#include <iostream>

using std::cout;
using std::endl;

int squareByValue( int );
void squareByReference( int & );

int main()
{
int x = 2;
int z = 4;


cout << "x = " << x << " before squareByValue\n";
cout << "Value returned by squareByValue: "
<< squareByValue( x ) << endl;
cout << "x = " << x << " after squareByValue\n" << endl;

cout << "z = " << z << " before squareByReference" << endl;
squareByReference( x );
cout << "z = " << z << "after squareByReference" << endl;



system("PAUSE");
return 0;
}

[Disch]

99 times out of 100, "undefined reference" or "unresolved external symbol" errors mean that you are calling a function that has no body.

In this case, your squareByValue and squareByReference functions do not have bodies (or the linker can't find the bodies).

Make sure you defined these functions.

[EricDu]

The errors are not caused by your typing, they mean that the linker cannot find the 2 symbols. To resolve the errors, you have to ask your teacher for the codes that define the 2 symbols.