函数名: freemem 
 功  能: 释放先前分配的DOS内存块 
 用  法: #include <alloc.h> 
         int freemem(unsigned seg); 
 程序例: 
#include <dos.h> 
 #include <alloc.h> 
 #include <stdio.h> 
int main(void) 
 { 
    unsigned int size, segp; 
    int stat; 
   size = 64; /* (64 x 16) = 1024 bytes */ 
    stat = allocmem(size, &segp); 
    if (stat < 0) 
       printf("Allocated memory at segment:\ 
       %x\n", segp); 
    else 
       printf("Failed: maximum number of\ 
       paragraphs available is %u\n", 
       stat); 
    freemem(segp); 
   return 0; 
 }