系统呼叫和库呼叫之间的区别

Key Difference – SystemCall vs Library Call

System call and Library call are related to the操作系统of a computer. The computer can operate in two modes; namely,user mode and kernel mode。这key differencebetween system call and library call is thatSystem call is a function provided by thekernelto enter kernel mode to access thehardware资源，而库呼叫是编程库提供的函数。For example, open () is a system call and fopen () is a library call. When fopen () inC program, uses the stdio.h header library. Then the system call ‘open (),’ is used from the kernel to complete the file opening task.

内容

1.Overview and Key Difference
2.什么是系统调用
3.什么是库
4.Similarities Between System Call and Library Call
5.并排比较 - 系统呼叫与图书馆以表格形式呼叫
6.概括

什么是系统电话？

计算机以两种模式运行。它们是用户模式和内核模式。某些过程正在计算机系统上运行。一个过程is a program in execution. When申请程序are running, the computer is in user mode. If a hardware resource is required, the process sends a request to the kernel, and the computer enters kernel mode. These requests are sent using system calls. The computer is switching between these two modes frequently. When the task is completed, the computer goes back to user mode from kernel mode. This mode transition is known as “context switching。” System calls are an interface between the operating system and user programs.

系统调用有多种类型。创建，终止过程，执行过程，分配和免费内存可以使用“Process Control System Calls。” “File Management System Calls” can be used to create, delete, read, write, open, close files. The process requires some resources to complete execution. Requesting and releasing devices are done through “Device Management System Calls。” “Information Management System Calls可以用来获取系统数据并获取过程和设备属性。流程正在相互交流。这种通信是使用“Communication System Calls。” Sending status information, creating and deleting communication connections and sending, receiving messages can be done using communication system calls.

什么是库?

Library call is a function provided by the programming libraries. Before making a library call, that library should be imported. Library call might depend on the system call.

InC language，这些功能可以在程序中通过包括标头文件来使用。使用预处理指令#include包括标头文件。预处理器扫描指定的文件，然后再继续使用源文件的其余部分。一些常见的库功能如下：“ Math.h”库包含与数学操作相关的功能。“ stdio.h”库提供了用于执行输入和输出的功能。“ fopen（）”打开了指向的文件名。“ fclose（）”关闭文件。“ printf（）用于将格式的输出发送到标准输出。“ fprintf（）”用于将格式的输出发送到流。“ scanf（）”用于从标准输入中读取格式的输入。 “stdlib.h” provides functions for memory management and “time.h” provides functions for time and date manipulation.

系统呼叫和库呼叫之间的相似性是什么？

• 相关操作system.

What is Difference Between System Call and Library Call?

System Call vs Library Call
系统调用是内核提供的函数，以输入内核模式以访问硬件资源。	Library call is a function provided by the programming library.
Mode of Execution
系统调用以内核模式执行。	一个Library call is executed in the user mode.
Mode Switching
一个System call switch from user mode to kernel mode.	这re is no switching from user mode to kernel mode in Library call.
Portability
一个System call is not portable.	一个Library call is portable.

概括– SystemCall vs Library Call

一个System call is implemented in the kernel, and a library call is implemented in the user space. The difference between system call and library call is that a system call is a function provided by the kernel to enter kernel mode to access hardware resources and library call is a function provided by programming libraries. Library calls might depend on the system calls to complete the task. open (), fork(), cd() are some examples of system calls. fopen (), fprintf () are examples of library calls.

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Reference:

1.Point, Tutorials. “C Header Files.”,Tutorials Point, 1 Nov. 2017.一个vailable here
2.Santhosh. “System Call v/s Library Function.” A Quest for Knowledge, 19 Aug. 2011.一个vailable here
3.Point, Tutorials. “C Library .”,Tutorials Point, 19 Sept. 2017.一个vailable here