universe@264: ---
universe@264: title: Modules
universe@264: ---
universe@259: 
universe@259: UCX provides several modules for data structures and algorithms.
universe@259: You may choose to use specific modules by inclueding the corresponding header
universe@259: file.
universe@259: Please note, that some modules make use of other UCX modules.
universe@259: For instance, the [Allocator](#allocator) module is used by many other modules
universe@259: to allow flexible memory allocation.
universe@259: By default the header files are placed into an `ucx` directory within your
universe@282: systems include directory. In this case you can use a module by including it
universe@259: via `#include <ucx/MODULENAME.h>`.
universe@259: Required modules are included automatically.
universe@259: 
universe@267: <div id="modules" align="center">
universe@267:     
universe@280: ----------------------- ----------------------      ----------------------------     -------------------------
universe@280: [Allocator](#allocator) [AVL&nbsp;Tree](#avl-tree)  [Buffer](#buffer)                [List](#list)
universe@280: [Logging](#logging)     [Map](#map)                 [Memory&nbsp;Pool](#memory-pool) [Properties](#properties)
universe@280: [Stack](#stack)         [String](#string)           [Testing](#testing)              [Utilities](#utilities)
universe@280: ----------------------- ----------------------      ----------------------------     -------------------------
universe@267: 
universe@267: </div>
universe@267: 
universe@259: ## Allocator
universe@259: 
universe@259: *Header file:* [allocator.h](api/allocator_8h.html)  
universe@259: *Required modules:* None.
universe@259: 
universe@259: A UCX allocator consists of a pointer to the memory area / pool and four
universe@259: function pointers to memory management functions operating on this memory
universe@259: area / pool. These functions shall behave equivalent to the standard libc
universe@259: functions `malloc`, `calloc`, `realloc` and `free`.
universe@259: 
universe@259: The signature of the memory management functions is based on the signature
universe@259: of the respective libc function but each of them takes the pointer to the
universe@259: memory area / pool as first argument.
universe@259: 
universe@259: As the pointer to the memory area / pool can be arbitrarily chosen, any data
universe@259: can be provided to the memory management functions. One example is the
universe@280: [UCX Memory Pool](#memory-pool).
universe@259: 
universe@259: ## AVL Tree
universe@259: 
universe@259: *Header file:* [avl.h](api/avl_8h.html)  
universe@259: *Required modules:* [Allocator](#allocator)
universe@259: 
universe@259: This binary search tree implementation allows average O(1) insertion and
universe@259: removal of elements (excluding binary search time).
universe@259: All common binary tree operations are implemented. Furthermore, this module
universe@259: provides search functions via lower and upper bounds.
universe@259: 
universe@287: ### Filtering items with a time window
universe@287: 
universe@287: Suppose you have a list of items which contain a `time_t` value and your task
universe@287: is to find all items within a time window `[t_start, t_end]`.
universe@287: With AVL Trees this is easy:
universe@287: ```C
universe@287: /* ---------------------
universe@287:  * Somewhere in a header
universe@287:  */
universe@287: typedef struct {
universe@287:     time_t ts;
universe@294:     /* other important data */
universe@287: } MyObject;
universe@287: 
universe@287: /* -----------
universe@287:  * Source code
universe@287:  */
universe@287: 
universe@287: UcxAVLTree* tree = ucx_avl_new(ucx_longintcmp);
universe@294: /* ... populate tree with objects, use '& MyObject.ts' as key ... */
universe@287: 
universe@287: 
universe@294: /* Now find every item, with 30 <= ts <= 70 */
universe@287: time_t ts_start = 30;
universe@287: time_t ts_end = 70;
universe@287: 
universe@287: printf("Values in range:\n");
universe@287: for (
universe@287:         UcxAVLNode* node = ucx_avl_find_node(
universe@287:             tree, (intptr_t) &ts_start,
universe@287:             ucx_longintdist, UCX_AVL_FIND_LOWER_BOUNDED);
universe@287:         node && (*(time_t*)node->key) <= ts_end;
universe@287:         node = ucx_avl_succ(node)
universe@287:     ) {
universe@287:     printf(" ts: %ld\n", ((MyObject*)node->value)->ts);
universe@287: }
universe@287: 
universe@287: ucx_avl_free_content(tree, free);
universe@287: ucx_avl_free(tree);
universe@287: ```
universe@287: 
universe@259: ## Buffer
universe@259: 
universe@259: *Header file:* [buffer.h](api/buffer_8h.html)  
universe@259: *Required modules:* None.
universe@259: 
universe@259: Instances of this buffer implementation can be used to read from or to write to
universe@259: memory like you would do with a stream. This allows the use of
universe@282: `ucx_stream_copy()` from the [Utilities](#utilities) module to copy contents
universe@282: from one buffer to another or from file or network streams to the buffer and
universe@259: vice-versa.
universe@259: 
universe@259: More features for convenient use of the buffer can be enabled, like automatic
universe@259: memory management and automatic resizing of the buffer space.
universe@259: See the documentation of the macro constants in the header file for more
universe@259: information.
universe@259: 
universe@290: ### Add line numbers to a file
universe@290: 
universe@290: When reading a file line by line, you have three options: first, you could limit
universe@290: the maximum supported line length.
universe@290: Second, you allocate a god buffer large
universe@290: enough for the most lines a text file could have.
universe@290: And third, undoubtedly the best option, you start with a small buffer, which
universe@290: adjusts on demand.
universe@290: An `UcxBuffer` can be created to do just that for you.
universe@290: Just pass the `UCX_BUFFER_AUTOEXTEND` option to the initialization function.
universe@290: Here is a full working program, which adds line numbers to a file.
universe@290: ```C
universe@290: #include <stdio.h>
universe@290: #include <ucx/buffer.h>
universe@290: #include <ucx/utils.h>
universe@290: 
universe@290: int main(int argc, char** argv) {
universe@290: 
universe@290:     if (argc != 2) {
universe@290:         fprintf(stderr, "Usage: %s <file>\n", argv[0]);
universe@290:         return 1;
universe@290:     }
universe@290: 
universe@290:     FILE* input = fopen(argv[1], "r");
universe@290:     if (!input) {
universe@290:         perror("Canno read input");
universe@290:         return 1;
universe@290:     }
universe@290: 
universe@290:     const size_t chunksize = 256;
universe@290: 
universe@290:     UcxBuffer* linebuf =
universe@290:         ucx_buffer_new(
universe@294:             NULL,       /* the buffer should manage the memory area for us */
universe@294:             2*chunksize,  /* initial size should be twice the chunk size */
universe@294:             UCX_BUFFER_AUTOEXTEND); /* the buffer will grow when necessary */
universe@290: 
universe@290:     size_t lineno = 1;
universe@290:     do {
universe@294:         /* read line chunk */
universe@290:         size_t read = ucx_stream_ncopy(
universe@290:                 input, linebuf, fread, ucx_buffer_write, chunksize);
universe@290:         if (read == 0) break;
universe@290:         
universe@294:         /* handle line endings */
universe@290:         do {
universe@290:             sstr_t bufstr = ucx_buffer_to_sstr(linebuf);
universe@290:             sstr_t nl = sstrchr(bufstr, '\n');
universe@290:             if (nl.length == 0) break;
universe@290: 
universe@290:             size_t linelen = bufstr.length - nl.length;
universe@290:             sstr_t linestr = sstrsubsl(bufstr, 0, linelen);
universe@290: 
universe@290:             printf("%zu: %" PRIsstr "\n", lineno++, SFMT(linestr));
universe@290: 
universe@294:             /* shift the buffer to the next line */
universe@290:             ucx_buffer_shift_left(linebuf, linelen+1);
universe@290:         } while(1);
universe@290: 
universe@290:     } while(1);
universe@290: 
universe@294:     /* print the 'noeol' line, if any */
universe@290:     sstr_t lastline = ucx_buffer_to_sstr(linebuf);
universe@290:     if (lastline.length > 0) {
universe@290:         printf("%zu: %" PRIsstr, lineno, SFMT(lastline));
universe@290:     }
universe@290: 
universe@290:     fclose(input);
universe@290:     ucx_buffer_free(linebuf);
universe@290: 
universe@290:     return 0;
universe@290: }
universe@290: ```
universe@290: 
universe@259: ## List
universe@259: 
universe@259: *Header file:* [list.h](api/list_8h.html)  
universe@259: *Required modules:* [Allocator](#allocator)
universe@259: 
universe@259: This module provides the data structure and several functions for a doubly
universe@259: linked list. Among the common operations like insert, remove, search and sort,
universe@259: we allow convenient iteration via a special `UCX_FOREACH` macro.
universe@259: 
universe@294: ### Remove duplicates from an array of strings
universe@294: 
universe@294: Assume you are given an array of `sstr_t` and want to create a list of these
universe@294: strings without duplicates.
universe@294: ```C
universe@294: #include <stdio.h>
universe@294: #include <ucx/list.h>
universe@294: #include <ucx/string.h>
universe@294: #include <ucx/utils.h>
universe@294: 
universe@294: UcxList* remove_duplicates(sstr_t* array, size_t arrlen) {
universe@294:     UcxList* list = NULL;
universe@294:     for (size_t i = 0 ; i < arrlen ; ++i) {
universe@294:         if (ucx_list_find(list, array+i, ucx_sstrcmp, NULL) == -1) {
universe@294:             sstr_t* s = malloc(sizeof(sstr_t));
universe@294:             *s = sstrdup(array[i]);
universe@294:             list = ucx_list_append(list, s);
universe@294:         }
universe@294:     }
universe@294:     return list;
universe@294: }
universe@294: 
universe@294: /* we will need this function to clean up the list contents later */
universe@294: void free_sstr(void* ptr) {
universe@294:     sstr_t* s = ptr;
universe@294:     free(s->ptr);
universe@294:     free(s);
universe@294: }
universe@294: 
universe@294: /* ... */
universe@294: 
universe@294: sstr_t* array = /* some array of strings */
universe@294: size_t arrlen = /* the length of the array */
universe@294: 
universe@294: UcxList* list = remove_duplicates(array,arrlen);
universe@294: 
universe@294: /* Iterate over the list and print the elements */
universe@294: UCX_FOREACH(elem, list) {
universe@294:     sstr_t s = *((sstr_t*)elem->data);
universe@294:     printf("%" PRIsstr "\n", SFMT(s));
universe@294: }
universe@294: 
universe@294: /* Use our free function to free the duplicated strings. */
universe@294: ucx_list_free_content(list, free_sstr);
universe@294: ucx_list_free(list);
universe@294: ```
universe@294: 
universe@259: ## Logging
universe@259: 
universe@259: *Header file:* [logging.h](api/logging_8h.html)  
universe@259: *Required modules:* [Map](#map), [String](#string)
universe@259: 
universe@259: The logging module comes with some predefined log levels and allows some more
universe@259: customization. You may choose if you want to get timestamps or source file and
universe@259: line number logged automatically when outputting a message.
universe@295: The following function call initializes a debug logger with all of the above
universe@295: information:
universe@295: ```C
universe@295:     log = ucx_logger_new(stdout, UCX_LOGGER_DEBUG,
universe@295:             UCX_LOGGER_LEVEL | UCX_LOGGER_TIMESTAMP | UCX_LOGGER_SOURCE);
universe@295: ```
universe@295: Afterwards you can use this logger with the predefined macros
universe@295: ```C
universe@295:     ucx_logger_trace(log, "Verbose output");
universe@295:     ucx_logger_debug(log, "Debug message");
universe@295:     ucx_logger_info(log, "Information");
universe@295:     ucx_logger_warn(log, "Warning");
universe@295:     ucx_logger_error(log, "Error message");
universe@295: ```
universe@295: or you use
universe@295: ```C
universe@295:     ucx_logger_log(log, CUSTOM_LEVEL, "Some message")
universe@295: ```
universe@295: When you use your custom log level, don't forget to register it with
universe@295: ```C
universe@295:     ucx_logger_register_level(log, CUSTOM_LEVEL, "CUSTOM")
universe@295: ```
universe@295: where the last argument must be a string literal.
universe@259: 
universe@259: ## Map
universe@259: 
universe@259: *Header file:* [map.h](api/map_8h.html)  
universe@259: *Required modules:* [Allocator](#allocator), [String](#string)
universe@259: 
universe@259: This module provides a hash map implementation using murmur hash 2 and separate
universe@259: chaining with linked lists. Similarly to the list module, we provide a
universe@259: `UCX_MAP_FOREACH` macro to conveniently iterate through the key/value pairs.
universe@259: 
universe@298: ### Parsing command line options
universe@298: 
universe@298: Assume you want to parse command line options and record them within a map.
universe@298: One way to do this is shown by the following code sample:
universe@298: ```C
universe@298:     UcxMap* options = ucx_map_new(16);
universe@298:     const char *NOARG = "";
universe@298:     
universe@298:     char *option = NULL;
universe@298:     char optchar = 0;
universe@298:     for(int i=1;i<argc;i++) {
universe@298:         char *arg = argv[i];
universe@298:         size_t len = strlen(arg);
universe@298:         if(len > 1 && arg[0] == '-') {
universe@298:             if(option) {
universe@298:                 fprintf(stderr,
universe@298:                         "Missing argument for option -%c\n", optchar);
universe@298:                 return 1;
universe@298:             }
universe@298:             for(int c=1;c<len;c++) {
universe@298:                 switch(arg[c]) {
universe@298:                     default: {
universe@298:                         fprintf(stderr, "Unknown option -%c\n\n", arg[c]);
universe@298:                         return 1;
universe@298:                     }
universe@298:                     case 'v': {
universe@298:                         ucx_map_cstr_put(options, "verbose", NOARG);
universe@298:                         break;
universe@298:                     }
universe@298:                     case 'o': {
universe@298:                         option = "output";
universe@298:                         optchar = 'o';
universe@298:                         break;
universe@298:                     }
universe@298:                 }
universe@298:             }
universe@298:         } else if(option) {
universe@298:             ucx_map_cstr_put(options, option, arg);
universe@298:             option = NULL;
universe@298:         } else {
universe@298:             /* ... handle argument that is not an option ... */
universe@298:         }
universe@298:     }
universe@298:     if(option) {
universe@298:         fprintf(stderr,
universe@298:                 "Missing argument for option -%c\n", optchar);
universe@298:         return 1;
universe@298:     }
universe@298: ```
universe@298: With the following loop, you can access the previously recorded options:
universe@298: ```C
universe@298:     UcxMapIterator iter = ucx_map_iterator(options);
universe@298:     char *arg;
universe@298:     UCX_MAP_FOREACH(optkey, arg, iter) {
universe@298:         char* opt = optkey.data;
universe@298:         if (*arg) {
universe@298:             printf("%s = %s\n", opt, arg);
universe@298:         } else {
universe@298:             printf("%s active\n", opt);
universe@298:         }
universe@298:     }
universe@298: ```
universe@298: Don't forget to call `ucx_map_free()`, when you are done with the map.
universe@298: 
universe@259: ## Memory Pool
universe@259: 
universe@259: *Header file:* [mempool.h](api/mempool_8h.html)  
universe@259: *Required modules:* [Allocator](#allocator)
universe@259: 
universe@259: Here we have a concrete allocator implementation in the sense of a memory pool.
universe@259: This pool allows you to register destructor functions for the allocated memory,
universe@259: which are automatically called on the destruction of the pool.
universe@259: But you may also register *independent* destructor functions within a pool in
universe@259: case, some external library allocated memory for you, which you wish to be
universe@259: destroyed together with this pool.
universe@259: 
universe@259: ## Properties
universe@259: 
universe@259: *Header file:* [properties.h](api/properties_8h.html)  
universe@259: *Required modules:* [Map](#map)
universe@259: 
universe@259: This module provides load and store function for `*.properties` files.
universe@259: The key/value pairs are stored within an UCX Map.
universe@259: 
universe@277: ### Example: Loading properties from a file
universe@277: 
universe@277: ```C
universe@294: /* Open the file as usual */
universe@277: FILE* file = fopen("myprops.properties", "r");
universe@277: if (!file) {
universe@277:     // error handling
universe@277:     return 1;
universe@277: }
universe@277: 
universe@294: /* Load the properties from the file */
universe@277: UcxMap* myprops = ucx_map_new(16);
universe@277: if (ucx_properties_load(myprops, file)) {
universe@294:     /* ... error handling ... */
universe@277:     fclose(file);
universe@277:     ucx_map_free(myprops);
universe@277:     return 1;
universe@277: }
universe@277: 
universe@294: /* Print out the key/value pairs */
universe@277: char* propval;
universe@277: UcxMapIterator propiter = ucx_map_iterator(myprops);
universe@277: UCX_MAP_FOREACH(key, propval, propiter) {
universe@277:     printf("%s = %s\n", (char*)key.data, propval);
universe@277: }
universe@277: 
universe@294: /* Don't forget to free the values before freeing the map */
universe@277: ucx_map_free_content(myprops, NULL);
universe@277: ucx_map_free(myprops);
universe@277: fclose(file);
universe@277: ```
universe@295: 
universe@259: ## Stack
universe@259: 
universe@259: *Header file:* [stack.h](api/stack_8h.html)  
universe@259: *Required modules:* [Allocator](#allocator)
universe@259: 
universe@259: This concrete implementation of an UCX Allocator allows you to grab some amount
universe@259: of memory which is then handled as a stack.
universe@259: Please note, that the term *stack* only refers to the behavior of this
universe@259: allocator. You may still choose if you want to use stack or heap memory
universe@259: for the underlying space.
universe@259: 
universe@259: A typical use case is an algorithm where you need to allocate and free large
universe@259: amounts of memory very frequently.
universe@259: 
universe@259: ## String
universe@259: 
universe@259: *Header file:* [string.h](api/string_8h.html)  
universe@259: *Required modules:* [Allocator](#allocator)
universe@259: 
universe@259: This module provides a safe implementation of bounded string.
universe@259: Usually C strings do not carry a length. While for zero-terminated strings you
universe@259: can easily get the length with `strlen`, this is not generally possible for
universe@259: arbitrary strings.
universe@259: The `sstr_t` type of this module always carries the string and its length to
universe@259: reduce the risk of buffer overflows dramatically.
universe@259: 
universe@267: ### Initialization
universe@267: 
universe@267: There are several ways to create an `sstr_t`:
universe@267: 
universe@267: ```C
universe@267: /* (1) sstr() uses strlen() internally, hence cstr MUST be zero-terminated */
universe@267: sstr_t a = sstr(cstr);
universe@267: 
universe@267: /* (2) cstr does not need to be zero-terminated, if length is specified */
universe@267: sstr_t b = sstrn(cstr, len);
universe@267: 
universe@267: /* (3) S() macro creates sstr_t from a string using sizeof() and using sstrn().
universe@267:        This version is especially useful for function arguments */
universe@267: sstr_t c = S("hello");
universe@267: 
universe@267: /* (4) ST() macro creates sstr_t struct literal using sizeof() */
universe@267: sstr_t d = ST("hello");
universe@267: ```
universe@267: 
universe@267: You should not use the `S()` or `ST()` macro with string of unknown origin,
universe@267: since the `sizeof()` call might not coincide with the string length in those
universe@267: cases. If you know what you are doing, it can save you some performance,
universe@267: because you do not need the `strlen()` call.
universe@267: 
universe@267: ### Finding the position of a substring
universe@267: 
universe@267: The `sstrstr()` function gives you a new `sstr_t` object starting with the
universe@267: requested substring. Thus determining the position comes down to a simple
universe@267: subtraction.
universe@267: 
universe@267: ```C
universe@267: sstr_t haystack = ST("Here we go!");
universe@267: sstr_t needle = ST("we");
universe@267: sstr_t result = sstrstr(haystack, needle);
universe@267: if (result.ptr)
universe@267:     printf("Found at position %zd.\n", haystack.length-result.length);
universe@267: else
universe@267:     printf("Not found.\n");
universe@267: ```
universe@267: 
universe@267: ### Spliting a string by a delimiter
universe@267: 
universe@267: The `sstrsplit()` function (and its allocator based version `sstrsplit_a()`) is
universe@267: very powerful and might look a bit nasty at a first glance. But it is indeed
universe@267: very simple to use. It is even more convenient in combination with a memory
universe@267: pool.
universe@267: 
universe@267: ```C
universe@267: sstr_t test = ST("here::are::some::strings");
universe@267: sstr_t delim = ST("::");
universe@267: 
universe@267: ssize_t count = 0; /* no limit */
universe@267: UcxMempool* pool = ucx_mempool_new_default();
universe@267: 
universe@267: sstr_t* result = sstrsplit_a(pool->allocator, test, delim, &count);
universe@267: for (ssize_t i = 0 ; i < count ; i++) {
universe@267:     /* don't forget to specify the length via the %*s format specifier */
universe@267:     printf("%*s\n", result[i].length, result[i].ptr);
universe@267: }
universe@267: 
universe@267: ucx_mempool_destroy(pool);
universe@267: ```
universe@267: The output is:
universe@267: 
universe@267:     here
universe@267:     are
universe@267:     some
universe@267:     strings
universe@267: 
universe@267: The memory pool ensures, that all strings are freed.
universe@267: 
universe@259: ## Testing
universe@259: 
universe@259: *Header file:* [test.h](api/test_8h.html)  
universe@259: *Required modules:* None.
universe@259: 
universe@259: This module provides a testing framework which allows you to execute test cases
universe@259: within test suites.
universe@259: To avoid code duplication within tests, we also provide the possibility to
universe@259: define test subroutines.
universe@259: 
universe@297: You should declare test cases and subroutines in a header file per test unit
universe@297: and implement them as you would implement normal functions.
universe@297: ```C
universe@297:     /* myunit.h */
universe@297:     UCX_TEST(function_name);
universe@297:     UCX_TEST_SUBROUTINE(subroutine_name, paramlist); /* optional */
universe@297: 
universe@297: 
universe@297:     /* myunit.c */
universe@297:     UCX_TEST_SUBROUTINE(subroutine_name, paramlist) {
universe@297:         /* ... reusable tests with UCX_TEST_ASSERT() ... */
universe@297:     }
universe@297: 
universe@297:     UCX_TEST(function_name) {
universe@297:         /* ... resource allocation and other test preparation ... */
universe@297: 
universe@297:         /* mandatory marker for the start of the tests */
universe@297:         UCX_TEST_BEGIN
universe@297: 
universe@297:         /*  ... verifications with UCX_TEST_ASSERT() ...
universe@297:          * (and/or calls with UCX_TEST_CALL_SUBROUTINE())
universe@297:          */
universe@297: 
universe@297:         /* mandatory marker for the end of the tests */
universe@297:         UCX_TEST_END
universe@297: 
universe@297:         /* ... resource cleanup ...
universe@297:          * (all code after UCX_TEST_END is always executed)
universe@297:          */
universe@297:     }
universe@297: ```
universe@297: If you want to use the `UCX_TEST_ASSERT()` macro in a function, you are
universe@297: *required* to use a `UCX_TEST_SUBROUTINE`.
universe@297: Otherwise the testing framework does not know where to jump, when the assertion
universe@297: fails.
universe@297: 
universe@297: After implementing the tests, you can easily build a test suite and execute it:
universe@297: ```C
universe@297:     UcxTestSuite* suite = ucx_test_suite_new();
universe@297:     ucx_test_register(suite, testMyTestCase01);
universe@297:     ucx_test_register(suite, testMyTestCase02);
universe@297:     /* ... */
universe@297:     ucx_test_run(suite, stdout); /* stdout, or any other FILE stream */
universe@297: ```
universe@297: 
universe@259: ## Utilities
universe@259: 
universe@259: *Header file:* [utils.h](api/utils_8h.html)  
universe@259: *Required modules:* [Allocator](#allocator), [String](#string)
universe@259: 
universe@259: In this module we provide very general utility function for copy and compare
universe@259: operations.
universe@259: We also provide several `printf` variants to conveniently print formatted data
universe@259: to streams or strings.
universe@259: 
universe@279: ### A simple copy program
universe@279: 
universe@279: The utilities package provides several stream copy functions.
universe@279: One of them has a very simple interface and can, for instance, be used to copy
universe@279: whole files in a single call.
universe@279: This is a minimal working example:
universe@279: ```C
universe@279: #include <stdio.h>
universe@279: #include <ucx/utils.h>
universe@279: 
universe@279: int main(int argc, char** argv) {
universe@279: 
universe@279:     if (argc != 3) {
universe@279:         fprintf(stderr, "Use %s <src> <dest>", argv[0]);
universe@279:         return 1;
universe@279:     }
universe@279: 
universe@294:     FILE *srcf = fopen(argv[1], "r");   /* insert error handling on your own */
universe@279:     FILE *destf = fopen(argv[2], "w");
universe@279:     
universe@279:     size_t n =  ucx_stream_copy(srcf, destf, fread, fwrite);
universe@279:     printf("%zu bytes copied.\n", n);
universe@279: 
universe@279:     fclose(srcf);
universe@279:     fclose(destf);
universe@279: 
universe@279: 
universe@279:     return 0;
universe@279: }
universe@279: ```
universe@279: 
universe@281: ### Automatic allocation for formatted strings
universe@279: 
universe@281: The UCX utility function `ucx_asprintf()` and it's convenient shortcut
universe@281: `ucx_sprintf` allow easy formatting of strings, without ever having to worry
universe@281: about the required space.
universe@281: ```C
universe@281: sstr_t mystring = ucx_sprintf("The answer is: %d!", 42);
universe@281: ```
universe@281: Still, you have to pass `mystring.ptr` to `free()` (or the free function of
universe@281: your allocator, if you use `ucx_asprintf`).
universe@281: If you don't have all the information ready to build your string, you can even
universe@281: use a [UcxBuffer](#buffer) as a target with the utility function
universe@281: `ucx_bprintf()`.
universe@281: ```C
universe@281: UcxBuffer* strbuffer = ucx_buffer_new(NULL, 512, UCX_BUFFER_AUTOEXTEND);
universe@281: 
universe@281: for (unsigned int i = 2 ; i < 100 ; i++) {
universe@281:         ucx_bprintf(strbuffer, "Integer %d is %s\n",
universe@281:                         i, prime(i) ? "prime" : "not prime");
universe@281: }
universe@281: 
universe@294: /* print the result to stdout */
universe@281: printf("%s", (char*)strbuffer->space);
universe@281: 
universe@281: ucx_buffer_free(strbuffer);
universe@281: ```