flowchart LR
A["1 — Character mapping"]
B["2 — Line splicing"]
C["3 — Tokenization"]
D["4 — Preprocessing"]
E["5 — Character-set mapping"]
F["6 — String concatenation"]
G["7 — Translation"]
H["8 — Linkage"]
A --> B --> C --> D --> E --> F --> G --> H
Effective C
Technical Books
My notes & review of Effective C by Robert C. Seacord
Notes
Introduction
Chapter 1. Getting Started With C
- The technical term for
#includeis a preprocessor directive which essentially does a copy/paste of that file in that location. - Header is a source file contains the definitions, function declarations, and constant definitions required by the users of the corresponding source file.
mainfunction is a defines the entry point for the program.- C defines two possible execution environments
- freestanding may not provide an OS and is typically used in embedded programming.
- A return from the initial call to the
mainfunction is equivalent to calling the C standard libraryexitfunction with the value returned by themainfunction as the argument.
- Five kinds of portability issues
- Implementation-Defined Behavior is a program behavior that’s not specified by the C standard and that may produce different results between implementations but has consistent, documented behavior with an implementation. An example is the number of bits in a byte.
- Unspecified Behavior is program behavior for which the standard provides two or more options but doesn’t mandate which option is chosen in any instance. Example is function parameter storage layout.
- Undefined Behavior is behavior that isn’t defined by the C standard. Example signed integer overflow and dereferencing an invalid pointer value. Undefined behaviors are identified in the standard as follows:
- Locale-Specific Behavior depends on local conventions of nationality, culture and language.
- Common extensions are widely used in many systems but are not portable to all implementations.
Chapter 2. Objects, Functions, And Types
No notes, was already pretty familiar with most content in this chapter.
Chapter 3. Arithmetic Types
- width is the number of bits used to represent a value of a given type excluding padding
- precision is the number of bits used to represent values, excluding sign and padding bits
- There are four kinds of integer constants:
- decimal e.g.
42 - octal e.g.
052 - hexadecimal e.g.
0x2A - binary e.g.
0b101010
- decimal e.g.
Chapter 4. Expressions and Operators
No notes, was already pretty familiar with most content in this chapter.
Chapter 5. Control Flow
No notes, was already pretty familiar with most content in this chapter.
Chapter 6. Dynamically Allocated Memory
- Memory managers are libraries that manage the heap fro you by providing implementations of the standard memory management functions.
- Memory manager runs as part of the client process.
- Allocations don’t go directly to the OS because it’s slower and works ony in big chunks of memory, whereas allocators split up those big chunks into little chunks.
- If
reallocsucceeds in allocating the new object, it callsfreeto deallocate the old object. If the allocation fails, thereallocfunction reatins the old object data at the same address and returns a null pointer.
// bad, don't do this. If realloc fails p is now a NULL ptr but realloc doesn't
// deallocate the storage that p references
size += 50;
if ( (p = realloc(p, size)) == NULL) return NULL:
// good, have a temp pointer
void *p = malloc(100);
void *temp;
// if realloc fails we still have reference to p and can free it
if ( (temp = realloc(p, size)) == NULL ) {
free(p);
return NULL;
}
// if it succeeds we can just update the pointer because realloc would have
// free p's original memory for us.
p = p2;- Important to note the freeing a nullptr is fine but calling
freetwice, aka a double free, is bad. Freeing doesn’t not change the ptr to NULL. - Pointers to already freed memory are known as dangling pointers. As already mentioned freeing a dangling ptr is a double free and using a ptr that has been freed is a use-after-free bug.
- When computing the size of a
structcontaining flexible array member using thesizeofoperator, the flexible array member is ignored.
Chapter 7. Strings
Chapter 8. Input/Output
- A Stream is a uniform abstraction for communicating with file and devices that consume or produce sequential data.
- Buffering is the process of temporarily storing data in memory that’s passing between a process and a device or file.
- Flushing is the process of taking the cached data in memory and writing to disk.
openestablishes a connection between a file identified by a path and a value called a file descriptor.- The
oflagparameter toopensets the file descriptors file access modes. Values for oflag are constructed by a bitwise-inclusive OR of a file access mode and any combination of access flags.
- TODO: Type of both the
fscanfand thefwriteexamples
Chapter 9. Preprocessor
Chapter 10. Program Structure
No notes.
Review
I thought the book was good but not one of my favorite resources. I feel Beej’s Guide to C Programming is a much better resource. I did learn some things that are not covered by that guide I am not sure it was worth reading the full book for that information.
Don’t get me wrong, the book contained great information but for me it didn’t read that well. I also was expecting some more advanced topics covered given this was an “Effective C” book and usually “Effective” books are target towards more advanced concepts whereas this was a more of an introductory book on a C.