warning: unused variable 'e' [-Wunused-variable]|

This is a warning message in programming that indicates that there is a variable declared in the code that is not being used.

For example, if you have the following code:

int a = 5;
int b = 10;
int c = a + b;
int e;

The variable "e" is declared but not used in any of the subsequent lines of code.

To resolve this warning, you can either remove the declaration of the unused variable "e" or use it in your code.