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1. How many bytes does size() report for the grinning face U+1F600 stored in a std::string?

1246

2. Which lead-byte pattern marks the start of a 2-byte UTF-8 character?

0110111011110

3. What does this program print? ``

cpp
#include <iostream>
#include <string>

int main() {
    std::string s = "na\U0001F600\U0001F600";
    int code_points = 0;
    for (char c : s) {
        if ((static_cast<unsigned char>(c) & 0xC0) != 0x80) ++code_points;
    }
    std::cout << s.size() << " " << code_points << "\n";
}

``

10 26 48 410 4

4. What does this program print? ``

cpp
#include <format>
#include <iostream>
#include <string>

int main() {
    std::string s = "\U0001F44D!";
    std::cout << s.size() << " " << std::format("{:02X}", static_cast<unsigned char>(s[0])) << "\n";
}

``

5 F02 F05 9F4 F0

5. True or false: every UTF-8 continuation byte starts with the bits 10, so (b & 0xC0) == 0x80 finds one.

True, because every continuation byte in UTF-8 has the pattern 10xxxxxxFalse, because continuation bytes start with 110, the same as a lead byte

Code points