It shows appropriate use of some system calls and library functions from c, including fopen, fclose, access, setvbuf, perror, strerror, and popen.

它演示了对一些系统调用和c库函数的适当使用，其中包括fopen、fclose、access、setvbuf、perror、strerror和popen。

youdao

Another is the system library functions precomposed by C language, which can be directly used by programmer.

研究了使自定义函数也成为系统库函数的方法，以提高使用C语言进行编程的效率。

youdao