What is the entrance point?

In computers, the input point is a point in the program, module or function where the code begins; Specifically, the memory address where it begins. The program is the first code module or even the first line of the code that is running. In the program, which is linear, such as Basic or Cobol, the entrance point is literally the first line of code. The code then follows gradually until a kind of jump or call is made. In modular programming, such as all variants of the C programming language, the input point is the initial module. V C, it is a "main ()" function.

In older programs and operating systems, the program could have multiple input points depending on the function or system. In most modern operating systems, including Windows® and Unix, programs are written in languages ​​that support a single entry point. Even in the first days of a modern computer, languages ​​such as Basic, with one entry point on the program, it can support "long jumps" where the program could "jump" from one modUl at the entrance point of another module indiscriminately. This was encouraged by what he called the "spaghetti code", which was difficult to maintain or modify.

The entry point may not even refer to the program entry point, but it can be the input point of the Dynamic Link Library (DLL), which are some mini -programs that are shared across other programs. One example is DLL, which controls the keyboard input. Regardless of the type of program, module or function, the entry point is the only point in which the processing of creatures in this piece of code. The key to understanding any language or adjustment and support of any program is to understand how the input point is identified in this particular program or operating system.

The concept of input points was implemented when computer programming left the linear methods of the first days. At that time, a computer program began on the first line of code and proceeded afterone line at the end of the process. Soon they created programming constructs such as a loop, conditional branching, recursion and more, programs that were more efficient, but the processing was reflected everywhere within the code. The nature of these programs means that there may be many lines or parts of the code before the point where the processing actually begins. For this reason, the entry point was created and identified.

in C, it became the main () function. No matter where this feature existed in the code, this is where the processing began. In other languages, the entry points are not identified as much where they are, but where they are not. The beginning of the program may contain parts of variable declarations and sub-routines. The first line of code after these areas or functions becomes an input point by default.