Search results
Results from the WOW.Com Content Network
An undefined variable in the source code of a computer program is a variable that is accessed in the code but has not been declared by that code. [1]In some programming languages, an implicit declaration is provided the first time such a variable is encountered at compile time.
In programming languages, name binding is the association of entities (data and/or code) with identifiers. [1] An identifier bound to an object is said to reference that object. Machine languages have no built-in notion of identifiers, but name-object bindings as a service and notation for the programmer is implemented by programming languages.
A global identifier is declared outside of functions and is available throughout the program. A local identifier is declared within a specific function and only available within that function. [1] For implementations of programming languages that are using a compiler, identifiers are often only compile time entities.
While a variable or function may be declared many times, it is typically defined once (in C++, this is known as the One Definition Rule or ODR). Dynamic languages such as JavaScript or Python generally allow functions to be redefined, that is, re-bound; a function is a variable much like any other, with a name and a value (the definition).
For example, in the snippet of Python code on the right, two functions are defined: square and sum_of_squares. square computes the square of a number; sum_of_squares computes the sum of all squares up to a number. (For example, square(4) is 4 2 = 16, and sum_of_squares(4) is 0 2 + 1 2 + 2 2 + 3 2 + 4 2 = 30.)
public class Shadow {private int myIntVar = 0; public void shadowTheVar {// Since it has the same name as above object instance field, it shadows above // field inside this method. int myIntVar = 5; // If we simply refer to 'myIntVar' the one of this method is found // (shadowing a second one with the same name) System. out. println (myIntVar); // prints 5 // If we want to refer to the ...
AOL Mail welcomes Verizon customers to our safe and delightful email experience!
Undeclared identifier, e.g.: doy.cpp: In function `int main()': doy.cpp:25: `DayOfYear' undeclared (first use this function) [3] This means that the variable "DayOfYear" is trying to be used before being declared. Common function undeclared, e.g.: xyz.cpp: In function `int main()': xyz.cpp:6: `cout' undeclared (first use this function) [3]