strstream(); | (1) | |
strstream(char* s, int n, std::ios_base::openmode mode
= std::ios_base::in | std::ios_base::out); | (2) |
Constructs new input/output strstream and its underlying std::strstreambuf.
1) Default-constructs the underlying
std::strstreambuf, which creates a dynamically growing buffer, and initializes the base class with the address of the strstreambuf member. 2) Initialized the base class with the address of the underlying
std::strstreambuf member, which is initialized in one of the two possible ways, both of which use a user-provided fixed-size array: a) if the
app bit is not set in mode, constructs the buffer by calling strstreambuf(s, n, s). The behavior is undefined if there are less than n elements in the array whose first element is pointed to by s b) if the
app bit is set in mode, constructs the buffer by calling strstreambuf(s, n, s + std::strlen(s)). The behavior is undefined if there are less than n elements in the array whose first element is pointed to by s or if the array does not contain a valid null-terminated character sequence.Parameters
| s | - | char array to use as the output buffer | ||||||||||||||
| n | - | size of the array to be used for output | ||||||||||||||
| mode | - | specifies stream open mode. It is a bitmask type, the following constants are defined (although only app is used):
|
Example
#include <iostream>
#include <strstream>
#include <string>
int main()
{
// dynamic buffer
std::strstream s1; // dynamic buffer
s1 << 1 << ' ' << 3.14 << " example" << std::ends;
std::cout << "buffer holds '" << s1.str() << "'\n";
s1.freeze(false);
int n; double d;
std::string w;
s1 >> n >> d >> w;
std::cout << "Read back: n = " << n
<< " d = " << d
<< " w = '" << w << "'\n";
// static buffer
char arr[20] = "-1 -3.14 ";
std::strstream s2(arr, sizeof arr, std::ios_base::app);
s2 << "another" << std::ends;
std::cout << "buffer holds: '" << s2.str() << "'\n";
s2 >> n >> d >> w;
std::cout << "Read back: n = " << n
<< " d = " << d
<< " w = '" << w << "'\n";
}Output:
buffer holds '1 3.14 example' Read back: n = 1 d = 3.14 w = 'example' buffer holds: '-1 -3.14 another' Read back: n = -1 d = -3.14 w = 'another'
See also
| constructs a strstreambuf object (public member function of std::strstreambuf) | |
| constructs an strstream, optionally allocating the buffer (public member function of std::istrstream) | |
| constructs an strstream, optionally allocating the buffer (public member function of std::ostrstream) |
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