这个程序怎么修改

#include<iostream>
using namespace std;
void main()
{
int sw=0;
while(sw==0)
{
    char str1[20];
    gets(str1);
    
    cout<<"str1 is :"<<endl;
    puts(str1);
    cout<<"0-继续,1-结束";
    cin>>sw;
    fflush(stdin);
  }
}

你输入的数据在缓冲呢.没进入内存.用这 fflush(stdin),表示把缓冲数据送内存,这样保证缓冲的数据释放掉.这样就不会出现错误.个人观点.
The fflush function flushes a stream. If the file associated with stream is open for output, fflush writes to that file the contents of the buffer associated with the stream. If the stream is open for input, fflush clears the contents of the buffer. fflush negates the effect of any prior call to ungetc against stream. Also, fflush(NULL) flushes all streams opened for output. The stream remains open after the call. fflush has no effect on an unbuffered stream.

Buffers are normally maintained by the operating system, which determines the optimal time to write the data automatically to disk: when a buffer is full, when a stream is closed, or when a program terminates normally without closing the stream. The commit-to-disk feature of the run-time library lets you ensure that critical data is written directly to disk rather than to the operating-system buffers. Without rewriting an existing program, you can enable this feature by linking the program’s object files with COMMODE.OBJ. In the resulting executable file, calls to _flushall write the contents of all buffers to disk. Only _flushall and fflush are affected by COMMODE.OBJ.