One thing that you may find useful from time to time is the ability
to build a string out of pieces. While this can be done to some extent
with the sprintf function, even that has its limits. The
objective of this project is to make a structure (similar to data_array_list example) that helps you
build strings. You need to create a structure called
string_builder and the functions given below. All functions
should use errno for error handling except for
string_buffer_destroy which is not allowed to fail.
You should also write a main function and some code to test your string builder to make sure it works correctly.
struct string_builder;
/* Creates a new string builder */
int string_builder_create(struct string_builder *sb);
/* Destroys a new string builder */
void string_builder_destroy(struct string_builder *sb);
/* Shrinks the string_builder to the given length. If the given length
* is greater than the current length, -1 is returned and errno is set
* to EINVAL.
*/
int string_builder_shrink(struct string_builder *sb, size_t length);
/* Appends the string "str" to the end of the string builder string */
int string_builder_append(struct string_builder *sb, char *str);
/* Appends a single character to the end of the string builder string */
int string_builder_append_char(struct string_builder *sb, char c);
/* Appends the first n characters of "str" to the string builder string */
int string_builder_append_n(struct string_builder *sb, char *str, size_t n);
/* Inserts the given string into the string builder at the given
* position. If the position is after the end, the function returns -1
* and errno is set to EINVAL. If the position is in the middle
* of the string, all of the characters at or after pos get shifted to
* the right to make room for the new string.
*/
int string_builder_insert(struct string_builder *sb, size_t pos, char *str);
/* Inserts the first n characters of the given string into the string
* builder at the given position.
*
* See also: string_builder_insert.
*/
int string_builder_insert_n(struct string_builder *sb, size_t pos,
char *str, size_t n);
/* Inserts a single character into the string builder at the given
* position.
*
* See also: string_builder_insert.
*/
int string_builder_insert_char(struct string_builder *sb, size_t pos,
char c, size_t n);
/* Retrieves the string from the string builder
*
* Note: The returned string is guaranteed to be null-terminated
*/
char * string_builder_get_string(struct string_builder *sb);
While this looks like a lot to implement, it isn’t nearly as bad as it looks. There is one particular function that, once you implement it, 5 of the others can be written in one line in terms of this function.