怎么查看动态分配内存空间的大小（c语言）

#include <stdio.h>

#include <malloc.h>

#include <stdlib.h>

int main( void )

{

long *buffer, *oldbuffer;

size_t size;

if( (buffer = (long *)malloc( 1000 * sizeof( long ) )) == NULL )

exit( 1 );

size = _msize( buffer );

printf( "Size of block after malloc of 1000 longs: %u/n", size );

// Reallocate and show new size:

oldbuffer = buffer; // save pointer in case realloc fails

if( (buffer = realloc( buffer, size + (1000 * sizeof( long )) ))

== NULL )

{

free( oldbuffer ); // free original block

exit( 1 );

}

size = _msize( buffer );

printf( "Size of block after realloc of 1000 more longs: %u/n",size );

free( buffer );

exit( 0 );

}

执行结果：

Size of block after malloc of 1000 longs: 4000

Size of block after realloc of 1000 more longs: 8000

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