The C++ std::ios::init() function is used to initialize the input/output stream object internal state. It is called ny stream constructors and assignment operators to set up the streams buffer, errors. It ensures that the stream is in a usable state before any operations are performed on it.
The init() function is not required for standard use cases, as the streams are initialized automatically by the c++ library.
The internal state is initialized in such a way that each of these members return the following values −
member function return value rdbuf sb tie0 rdstate goodbit if sb is not a null pointer, badbit otherwise exceptions goodbit flags skipws | dec width 0 precision 6 fill ' ' (whitespace) getloc a copy of locale() Syntax
Following is the syntax for std::ios::init() function.
protected:void init (streambuf* sb);Parameters
This function does not return anything.
ExceptionsIf an exception is thrown, the stream is in a valid state.
Data racesModifies the stream object. The object pointed by sb may be accessed and/or modified.
Concurrent access to the same stream object or stream buffer may cause data races.
ExampleIn the following example, we are going to consider the basic usage of the init() function.
#include <iostream>
int main()
{
std::ostream a(nullptr);
a.setstate(std::ios::failbit);
std::cout << "TutorialsPoint." << std::endl;
return 0;
}
Output
Output of the above code is as follows −
TutorialsPoint.
ios.htm
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