Runtime vs. Compile time

Question

What is the difference between run-time and compile-time?

Answer 1

Compile time: Time taken to convert the source code into a machine code so that it becomes an executable is called compile time.

Run time: When an application is running, it is called run time.

Compile time errors are those syntax errors, missing file reference errors. Runtime errors happen after the source code has been compiled into an executable program and while the program is running. Examples are program crashes, unexpected program behavior or features don't work.

Answer 2

I have always thought of it relative to program processing overhead and how it affects preformance as previously stated. A simple example would be, either defining the absolute memory required for my object in code or not.

A defined boolean takes x memory this is then in the compiled program and cannot be changed. When the program runs it knows exactly how much memory to allocate for x.

On the other hand if I just define a generic object type (i.e. kind of a undefined place holder or maybe a pointer to some giant blob) the actual memory required for my object is not known until the program is run and I assign something to it, thus it then must be evaluated and memory allocation, etc. will be then handled dynamically at run time (more run time overhead).

How it is dynamically handled would then depend on the language, the compiler, the OS, your code, etc.

On that note however it would really depends on the context in which you are using run time vs compile time.

Answer 3

It's not a good question for S.O. (it's not a specific programming question), but it's not a bad question in general.

If you think it's trivial: what about read-time vs compile-time, and when is this a useful distinction to make? What about languages where the compiler is available at runtime? Guy Steele (no dummy, he) wrote 7 pages in CLTL2 about EVAL-WHEN, which CL programmers can use to control this. 2 sentences are barely enough for a definition, which itself is far short of an explanation.

In general, it's a tough problem that language designers have seemed to try to avoid. They often just say "here's a compiler, it does compile-time things; everything after that is run-time, have fun". C is designed to be simple to implement, not the most flexible environment for computation. When you don't have the compiler available at runtime, or the ability to easily control when an expression is evaluated, you tend to end up with hacks in the language to fake common uses of macros, or users come up with Design Patterns to simulate having more powerful constructs. A simple-to-implement language can definitely be a worthwhile goal, but that doesn't mean it's the end-all-be-all of programming language design. (I don't use EVAL-WHEN much, but I can't imagine life without it.)

And the problemspace around compile-time and run-time is huge and still largely unexplored. That's not to say S.O. is the right place to have the discussion, but I encourage people to explore this territory further, especially those who have no preconceived notions of what it should be. The question is neither simple nor silly, and we could at least point the inquisitor in the right direction.

Unfortunately, I don't know any good references on this. CLTL2 talks about it a bit, but it's not great for learning about it.

Answer 4

Here is an extension to the Answer to the question "difference between run-time and compile-time?" -- Differences in overheads associated with run-time and compile-time?

The run-time performance of the product contributes to its quality by delivering results faster. The compile-time performance of the product contributes to its timeliness by shortening the edit-compile-debug cycle. However, both run-time performance and compile-time performance are secondary factors in achieving timely quality. Therefore, one should consider run-time and compile-time performance improvements only when justified by improvements in overall product quality and timeliness.

A great source for further reading here:

Answer 5

here's a very simple answer:

Runtime and compile time are programming terms that refer to different stages of software program development. In order to create a program, a developer first writes source code, which defines how the program will function. Small programs may only contain a few hundred lines of source code, while large programs may contain hundreds of thousands of lines of source code. The source code must be compiled into machine code in order to become and executable program. This compilation process is referred to as compile time.(think of a compiler as a translator)

A compiled program can be opened and run by a user. When an application is running, it is called runtime.

The terms "runtime" and "compile time" are often used by programmers to refer to different types of errors. A compile time error is a problem such as a syntax error or missing file reference that prevents the program from successfully compiling. The compiler produces compile time errors and usually indicates what line of the source code is causing the problem.

If a program's source code has already been compiled into an executable program, it may still have bugs that occur while the program is running. Examples include features that don't work, unexpected program behavior, or program crashes. These types of problems are called runtime errors since they occur at runtime.

The reference

Answer 6

we can classify these under different two broad groups static binding and dynamic binding. It is based on when the binding is done with the corresponding values. If the references are resolved at compile time, then it is static binding and if the references are resolved at runtime then it is dynamic binding. Static binding and dynamic binding also called as early binding and late binding. Sometimes they are also referred as static polymorphism and dynamic polymorphism.

Joseph Kulandai‏.