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The declaration-list declares variables to be used in that scope, and the statement-list are the actions to be performed. Brackets define their own scope, and variables defined inside those brackets will be automatically deallocated at the closing bracket. Declarations and statements can be freely intermixed within a compound statement (as in C++).
The C++ Standard Library provides several generic containers, functions to use and manipulate these containers, function objects, generic strings and streams (including interactive and file I/O), support for some language features, and functions for common tasks such as finding the square root of a number.
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]
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 information in the header file provides the interface between code that uses the declaration and that which defines it, a form of information hiding. A declaration is often used in order to access functions or variables defined in different source files, or in a library. A mismatch between the definition type and the declaration type ...
:For var«s»:In list statements:EndFor:For var«s»:InEach list statements:EndFor: C instructions can be a single statement or a block in the form of: { statements} while (condition) instructions: do instructions while (condition); for («type» i = first; i <= last; i++) instructions — Objective-C: for (type item in set) instructions: C++ (STL)
The C library provides a basic set of mathematical functions, string manipulation, type conversions, and file and console-based I/O. It does not include a standard set of " container types " like the C++ Standard Template Library , let alone the complete graphical user interface (GUI) toolkits, networking tools, and profusion of other ...
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 ...