5 String and Array Utilities

Operations on strings (or arrays of characters) are an important part of many programs. The GNU C library provides an extensive set of string utility functions, including functions for copying, concatenating, comparing, and searching strings. Many of these functions can also operate on arbitrary regions of storage; for example, the memcpy function can be used to copy the contents of any kind of array.

It's fairly common for beginning C programmers to “reinvent the wheel” by duplicating this functionality in their own code, but it pays to become familiar with the library functions and to make use of them, since this offers benefits in maintenance, efficiency, and portability.

For instance, you could easily compare one string to another in two lines of C code, but if you use the built-in strcmp function, you're less likely to make a mistake. And, since these library functions are typically highly optimized, your program may run faster too.

• Representation of Strings: Introduction to basic concepts.
• String/Array Conventions: Whether to use a string function or an arbitrary array function.
• String Length: Determining the length of a string.
• Copying and Concatenation: Functions to copy the contents of strings and arrays.
• String/Array Comparison: Functions for byte-wise and character-wise comparison.
• Collation Functions: Functions for collating strings.
• Search Functions: Searching for a specific element or substring.
• Finding Tokens in a String: Splitting a string into tokens by looking for delimiters.
• strfry: Function for flash-cooking a string.
• Trivial Encryption: Obscuring data.
• Encode Binary Data: Encoding and Decoding of Binary Data.
• Argz and Envz Vectors: Null-separated string vectors.