Answered: For this week's conversation, since we…

Database System Concepts

7th Edition

ISBN:9780078022159

Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Publisher:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan

Chapter1: Introduction

Section: Chapter Questions

Problem 1PE

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For this week's conversation, since we are talking about functions, most other programming languages have a main function. Python, on the other hand, does not have a main function unless we define it. Why does Python not have a main function

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This is related both to linker and operating system behaviors and language design. C code is called directly (natively) by operating system, which has to know where to start among the many exported symbols.
If this is a library instead of an exe, the entry point can be any exported symbol (function) the calling program uses. If it is an exe, the OS follows a convention and calls a function with a particular name. On Unix in userland it is the main() function called by libc, in other environments it can be different: winmain() in windows, start_kernel() called by the bootload if it’s a Linux kernel started by the bootloader.
In the case of python, the language does not rely at all on OS called. The OS merely calls a program called “python” which then does whatever it likes, really it is translating some intermediate language to successive calls to C functions (coded inside the python software) with the right parameters.
That means the language designer had the possibility to do whatever he felt like to define the program workflow.

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