std::ostrstream::freeze

 

C++

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I/O 操作符

打印函数 (C++23)

C 样式 I/O

缓冲区

basic_streambuf

basic_filebuf

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strstreambuf (C++98/26*)

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ios_base

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iostream_category (C++11)

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std::ostrstream

成员函数

ostrstream::ostrstream

ostrstream::~ostrstream

ostrstream::rdbuf

ostrstream::str

ostrstream::freeze

ostrstream::pcount

 

void freeze( bool flag = true );		(在 C++98 中已弃用) (在 C++26 中已移除)

如果流使用动态分配的数组用于输出，则禁用 (flag == true) 或启用 (flag == false) 缓冲区的自动分配/释放。实际上调用 rdbuf()->freeze(flag).

注释

调用 str() 后，动态流将自动冻结。在退出创建此 ostrstream 对象的范围之前，需要调用 freeze(false)，否则析构函数将导致内存泄漏。此外，一旦达到分配缓冲区的末尾，向冻结流的额外输出可能会被截断。

参数

flag

-

所需状态

返回值

(无)

示例

运行此代码

#include <iostream>
#include <strstream>
 
int main()
{
    std::ostrstream dyn; // dynamically-allocated output buffer
    dyn << "Test: " << 1.23; // note: no std::ends to demonstrate appending
    std::cout << "The output stream contains \"";
    std::cout.write(dyn.str(), dyn.pcount()) << "\"\n";
    // the stream is now frozen due to str()
    dyn << " More text"; // output to a frozen stream may be truncated
    std::cout << "The output stream contains \"";
    std::cout.write(dyn.str(), dyn.pcount()) << "\"\n";
    dyn.freeze(false); // freeze(false) must be called or the  destructor will leak
 
    std::ostrstream dyn2; // dynamically-allocated output buffer
    dyn2 << "Test: " << 1.23; // note: no std::ends
    std::cout << "The output stream contains \"";
    std::cout.write(dyn2.str(), dyn2.pcount()) << "\"\n";
    dyn2.freeze(false);   // unfreeze the stream after str()
    dyn2 << " More text" << std::ends; // output will not be truncated (buffer grows)
    std::cout << "The output stream contains \"" << dyn2.str() << "\"\n";
    dyn2.freeze(false); // freeze(false) must be called or the  destructor will leak 
}

可能的输出

The output stream contains "Test: 1.23"
The output stream contains "Test: 1.23 More "
The output stream contains "Test: 1.23"
The output stream contains "Test: 1.23 More text"

另请参阅

freeze

设置/清除缓冲区的冻结状态 (std::strstreambuf 的公共成员函数)