std::strstreambuf::freeze

std：：strStrebuf：：冻结

void freeze( bool freezefl = true

如果缓冲区使用动态分配，则将流的冻结状态设置为freezefl...

当溪流被冻结时，overflow()将不会重新分配缓冲区和destructor不会释放缓冲区%28，从而导致内存泄漏%29。

参数

freezefl	-	new value to set the freeze status to

返回值

%280%29

注记

每一次呼叫str()冻结流以保留它返回的指针的有效性。若要允许析构函数释放缓冲区，freeze(false)需要显式调用。

例

在本例中，基础数组的初始分配为16个字节。

二次

#include <strstream>
#include <iostream>
 
int main()
{
    {
        std::strstream dyn; // dynamically-allocated read/write buffer
        dyn << "Test: " << 1.23; // note: no std::ends to demonstrate append behavior
        std::cout << "dynamic buffer holds " << dyn.pcount() << " characters: '";
        std::cout.write(dyn.str(), dyn.pcount()) << "'\n";
        // the buffer is now frozen, further output will not make the buffer grow
        dyn << "more output, hopefully enough to run out of the allocated space" << std::ends;
        std::cout << "After more output, it holds "
                  << dyn.pcount() << " characters: '" << dyn.str() << "'\n";
        dyn.freeze(false // unfreeze before destructor
    } // memory freed by the destructor
 
    {
        char arr[20];
        std::ostrstream st(arr, sizeof arr // fixed-size buffer
        st << 1.23; // note: no std::ends to demonstrate append behavior
        std::cout << "static buffer holds "
                  << st.pcount() << " characters: '";
        std::cout.write(st.str(), st.pcount()
        std::cout << "'\n";
        st << "more output, hopefully enough to run out of the allocated space" << std::ends;
        std::cout << "static buffer holds "
                  << st.pcount() << " characters: '";
        std::cout.write(st.str(), st.pcount()
        std::cout << "'\n";
    } // nothing to deallocate, no need to unfreeze,
}

二次

产出：

二次

dynamic buffer holds 10 characters: 'Test: 1.23'
After more output, it holds 16 characters: 'Test: 1.23more o'
static buffer holds 4 characters: '1.23'
static buffer holds 20 characters: '1.23more output, hop'

二次

另见

freeze	disables/enables automatic reallocation (public member function of std::strstream)
freeze	disables/enables automatic reallocation (public member function of std::ostrstream)
(destructor) virtual	destructs a strstreambuf object, optionally deallocating the character array (virtual public member function)
overflow virtual	appends a character to the output sequence, may reallocate or initially allocate the buffer if dynamic and not frozen (virtual protected member function)

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