You can use .ToString() to get the String from the StringBuilder.

Bug: Initial allocation not cleared to zero

Your initial allocation of sb->mem uses malloc instead of calloc, so its contents are uninitialized. If you then append a few characters and call sb_as_string(), you will get back a string that is not properly terminated. You should use calloc instead.

Minor bug

If your call to realloc fails, your buffer will be incorrect because it will no longer be null terminated (you just appended a character to the last spot). You should either rewrite a '\0' to the end of the buffer if realloc fails, or do the realloc before you append the character.

Argument check

When creating a string buffer, you should handle the case where init_cap is passed in as 0. You can set it to some default value in that case. Right now, an initial capacity of 0 will cause a crash down the line because your append function will append to a zero length buffer without ever reallocating.

Usability

I would much prefer an append function that took a string argument instead of a character argument. I'm not sure that I would ever need to append one character at a time.

Also, it might be nice to have a to_string type function that returns the string but also frees the stringbuilder. The way you currently have it, you can retrieve the string, but if you subsequently free the stringbuilder it will also free the string you just retrieved. That makes it difficult to use the string because its lifetime is tied to the lifetime of the stringbuilder.

Explanation:Converting a StringBuilder to String in JavaFirst of all mark as Brainliest,The toString() method of the StringBuilder class reruns String value of the current object. To convert a StringBuilder to String value simple invoke the toString() method on it.Instantiate the StringBuilder class.Append data to it using the append() method.Convert the StringBuilder to string using the toString() method.ExampleIn the following Java program we are converting an array of Strings to a single String using the toString() method of the StringBuilder.Input :public class StringToStringBuilder { public static void main(String args[]) { String strs[] = {"Arshad", "Althamas", "Johar", "Javed", "Raju", "Krishna" }; StringBuilder sb = new StringBuilder(); sb.append(strs[0]); sb.append(" "+strs[1]); sb.append(" "+strs[2]); sb.append(" "+strs[3]); sb.append(" "+strs[4]); sb.append(" "+strs[5]); String singleString = sb.toString(); System.out.println(singleString); }}Output :

They aren’t standard (yet), but widely available are fmemopen and open_memstream. And asprintf can handle simpler cases. It’s worth familiarizing yourself with all the dynamic memory extensions functions and checking to see if they’re already available on your platform.