PA1 Resubmission: Due Date 10/23 at 11:59pm

If you want to resubmit PA1, please read this section carefully. You need to pass all the tests in the original PA1, while also implementing an extra function described below.

void next_utf8_char(char str[], int32_t cpi, char result[])

Takes a UTF-8 encoded string and a codepoint index. Calculates the codepoint at that index. Then, calculates the code point with value one higher (so e.g. for ”é“ U+00E9 that would be “ê” (U+00EA), and for “🐩” (U+1F429) that would be “🐪” (U+1F42A)). Saves the encoding of that code point in the result array starting at index 0.

Example Usage:

char str[] = "Joséph";
char result[100];
int32_t idx = 3;
next_utf8_char(str, idx, result);
printf("Next Character of Codepoint at Index 3: %s\n",result);
// 'é' is the 4th codepoint represented by the bytes 0xC3 0xA9
// 'ê' in UTF-8 hex bytes is represented as 0xC3 0xAA

=== Output ===
Next Character of Codepoint at Index 3: ê

Now, Your final output on running the utfanalyzer code that will be graded should contain this extra line:

Next Character of Codepoint at Index 3: FILL

Note: If the number of codepoints in the input string is less than 4, this added line would only have the prompt without any character as follows:

Next Character of Codepoint at Index 3:

The complete program output for example, should look like:

$ ./utf8analyzer
Enter a UTF-8 encoded string: My 🐩’s name is Erdős.
Valid ASCII: false
Uppercased ASCII: "MY 🐩’S NAME IS ERDőS."
Length in bytes: 27
Number of code points: 21
Bytes per code point: 1 1 1 4 3 1 1 1 1 1 1 1 1 1 1 1 1 1 2 1 1
Substring of the first 6 code points: "My 🐩’s"
Code points as decimal numbers: 77 121 32 128041 8217 115 32 110 97 109 101 32 105 115 32 69 114 100 337 115 46
Animal emojis: 🐩
Next Character of Codepoint at Index 3: 🐪

(All our tests will check for this newly added line, in addition to lines from the original PA)

You will also need to answer the following updated DESIGN question in your resubmission

Consider the 3-byte sequence 11100000 10000000 10100001. Answer the following questions:

  • What code point does it encode in UTF-8, and what character is that?
  • What are the three other ways to encode that character?
  • Give an example of a character that has exactly three encodings (but not four, like the one in the previous example does)
  • What are some problems with having these multiple encodings, especially for ASCII characters? A web search for “overlong UTF-8 encoding” may be useful here.