Book Image

Extreme C

By : Kamran Amini
5 (1)
Book Image

Extreme C

5 (1)
By: Kamran Amini

Overview of this book

There’s a lot more to C than knowing the language syntax. The industry looks for developers with a rigorous, scientific understanding of the principles and practices. Extreme C will teach you to use C’s advanced low-level power to write effective, efficient systems. This intensive, practical guide will help you become an expert C programmer. Building on your existing C knowledge, you will master preprocessor directives, macros, conditional compilation, pointers, and much more. You will gain new insight into algorithm design, functions, and structures. You will discover how C helps you squeeze maximum performance out of critical, resource-constrained applications. C still plays a critical role in 21st-century programming, remaining the core language for precision engineering, aviations, space research, and more. This book shows how C works with Unix, how to implement OO principles in C, and fully covers multi-processing. In Extreme C, Amini encourages you to think, question, apply, and experiment for yourself. The book is essential for anybody who wants to take their C to the next level.
Table of Contents (23 chapters)

Changes to fopen function

The fopen function is usually used for opening a file and returning a file descriptor to that file. The concept of a file is very general in Unix, and by using the term file, we don't necessarily mean a file located on the filesystem. The fopen function has the following signatures:

FILE* fopen(const char *pathname, const char *mode);
FILE* fdopen(int fd, const char *mode);
FILE* freopen(const char *pathname, const char *mode, FILE *stream);

Code Box 12-2: Various signatures of the family of fopen functions

As you can see, all of the preceding signatures accept a mode input. This input parameter is a string that determines how the file should be opened. The following description in Shell Box 12-2 is obtained from the FreeBSD manual for the fopen function and explains how mode should be used:

$ man 3 fopen
The argument mode points to a string beginning with one of the following letters:
     "r"     Open for reading.  The...