ostrstream(); | (1) | |
ostrstream(char* s, int n, std::ios_base::openmode mode = std::ios_base::out); | (2) |
Constructs new 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 write to 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 as the output buffer | ||||||||||||||
| 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>
int main()
{
std::ostrstream s1; // dynamic buffer
s1 << 1 << ' ' << 3.14 << " example\n" << std::ends;
std::cout << s1.str();
s1.freeze(false);
char arr[15] = "Hello";
std::ostrstream s2(arr, sizeof arr, std::ios_base::app);
s2 << ", world!" << std::ends;
std::cout << s2.str() << '\n';
std::cout << arr << '\n'; // streams use the provided arrays
}Output:
1 3.14 example Hello, world! Hello, world!
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::strstream) |
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