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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]
Most of the functions that operate on C strings are declared in the string.h header (cstring in C++), while functions that operate on C wide strings are declared in the wchar.h header (cwchar in C++). These headers also contain declarations of functions used for handling memory buffers; the name is thus something of a misnomer.
The C programming language provides many standard library functions for file input and output.These functions make up the bulk of the C standard library header <stdio.h>. [1] The functionality descends from a "portable I/O package" written by Mike Lesk at Bell Labs in the early 1970s, [2] and officially became part of the Unix operating system in Version 7.
Bjarne Stroustrup, the creator of C++, wrote the first version of the stream I/O library in 1984, as a type-safe and extensible alternative to C's I/O library. [5] The library has undergone a number of enhancements since this early version, including the introduction of manipulators to control formatting, and templatization to allow its use with character types other than char.
The formatting placeholders in scanf are more or less the same as that in printf, its reverse function.As in printf, the POSIX extension n$ is defined. [2]There are rarely constants (i.e., characters that are not formatting placeholders) in a format string, mainly because a program is usually not designed to read known data, although scanf does accept these if explicitly specified.
A program may also accept string input from its user. Further, strings may store data expressed as characters yet not intended for human reading. Example strings and their purposes: A message like "file upload complete" is a string that software shows to end users. In the program's source code, this message would likely appear as a string literal.
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. See for example Concatenation below.
The current object's data is de-allocated. The object that is being moved from must have its data marked as nullptr (or something to signify the move) The operator must return a reference to "*this". Consider the following move assignment operator for a simple string class: [2]