forward reference extends over definition of value res

A forward reference extends over the definition of a variable or value. This means that the reference to the variable or value is made before it is actually defined or assigned a value. This can lead to errors in the program because the reference is trying to access a value that does not exist yet.

For example, consider the following code:

public class Example {
    int num = doubleNum;
    int doubleNum = num * 2;
}

In this code, the variable num is assigned the value of doubleNum before doubleNum is defined. This is a forward reference because the reference to doubleNum comes before its definition. This code will result in an error because doubleNum is not yet defined when it is referenced in the assignment of num.

To fix this issue, the code can be rearranged to define and assign values before they are referenced:

public class Example {
    int doubleNum = num * 2;
    int num = doubleNum;
}

In this updated code, doubleNum is defined and assigned a value before it is referenced in the assignment of num. This ensures that the values are defined and assigned in the correct order, avoiding any forward reference errors