What is the difference between the use and require statements in Perl?

In Perl, the "use" and "require" statements are used to load and include modules in a program. Both statements are used to load external modules and make their functions and variables available to the current script, but they have some key differences in how they work and when they are used.

The "use" statement is used to load and import a module at compile-time. This means that the module is loaded and processed when the script is compiled, before it is executed. The "use" statement is typically used to load modules that are required throughout the entire script, such as modules that define basic functions or that set up global variables. The "use" statement also calls the import method of the module, this is a method that allows the module to export its functions and variables, so they can be used in the current namespace.

The "require" statement is used to load a module at runtime. This means that the module is loaded and processed when the require statement is executed, during the execution of the script. The "require" statement is typically used to load modules that are only needed in specific parts of the script, such as modules that are only needed for certain functions or that are only needed under certain conditions. Unlike the "use" statement, the "require" statement only loads the module, it doesn't call import method.

Another difference is that, "require" statement also returns a value indicating whether the required module was successfully loaded or not, this can be used in conditional statements.

In summary, the main difference between the "use" and "require" statements in Perl is when they are used. The "use" statement is used to load modules at compile-time, and it also calls the import method of the module, making its functions and variables available in the current namespace. The "require" statement is used to load modules at runtime, it only loads the module, it doesn't call import method and it also returns a value indicating whether the module was successfully loaded or not.