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A string is defined as a contiguous sequence of code units terminated by the first zero code unit (often called the NUL code unit). [1] This means a string cannot contain the zero code unit, as the first one seen marks the end of the string. The length of a string is the number of code units before the zero code unit. [1]
The std::string class is the standard representation for a text string since C++98. The class provides some typical string operations like comparison, concatenation, find and replace, and a function for obtaining substrings. An std::string can be constructed from a C-style string, and a C-style string can also be obtained from one. [7]
This allows the string to contain NUL and made finding the length need only one memory access (O(1) (constant) time), but limited string length to 255 characters. C designer Dennis Ritchie chose to follow the convention of null-termination to avoid the limitation on the length of a string and because maintaining the count seemed, in his ...
The \n escape sequence allows for shorter code by specifying the newline in the string literal, and for faster runtime by eliminating the text formatting operation. Also, the compiler can map the escape sequence to a character encoding system other than ASCII and thus make the code more portable.
Like raw strings, there can be any number of equals signs between the square brackets, provided both the opening and closing tags have a matching number of equals signs; this allows nesting as long as nested block comments/raw strings use a different number of equals signs than their enclosing comment: --[[comment --[=[ nested comment ...
Null character for indicating the end of a null-terminated string. Null pointer for indicating the end of a linked list or a tree. A set most significant bit in a stream of equally spaced data values, for example, a set 8th bit in a stream of 7-bit ASCII characters stored in 8-bit bytes indicating a special property (like inverse video ...
For function that manipulate strings, modern object-oriented languages, like C# and Java have immutable strings and return a copy (in newly allocated dynamic memory), while others, like C manipulate the original string unless the programmer copies data to a new string.
But it comes with a performance penalty for string literals, as std::string usually allocates memory dynamically, and must copy the C-style string literal to it at run time. Before C++11, there was no literal for C++ strings (C++11 allows "this is a C++ string"s with the s at the end of the literal), so the normal constructor syntax was used ...