Iterate Objects of Unknown Length with a Sentinel
Learn to iterate objects of unknown length with a sentinel.
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Some objects don’t have a specific length. To know their length, we need to iterate through all their elements. For example, elsewhere in this chapter we’ve seen a generator that doesn’t have a specific length. A more common example would be a C-string.
A C-string is a primitive C-array of characters, terminated with a null '\0' value.
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A C-string with its null terminator
We use C-strings all the time, even if we don’t realize it. Any literal string in C/C++ is a C-string:
std::string s = "string";
Here, the STL string s is initialized with a literal string. The literal string is a C-string. If we look at the individual characters in hexadecimal, we’ll see the null terminator:
for (char c : "string") {std::cout << format("{:02x} ", c);}
The word “string” ...