1: void streaming_property(FILE* file)

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   2: {

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   3: 

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   4:         if(file->_flags & _IO_UNBUFFERED) 

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   5:                 printf("unbuffered/n");

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   6:         else if(file->_flags & _IO_LINE_BUF)

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   7:                 printf("line-buffered/n");

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   8:         else

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   9:                 printf("fully-buffered/n");

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  10: 

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  11:         printf("buffer size is %d/n", file->_IO_buf_end - 

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  12:
 
                                 file->_IO_buf_base); 

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  13: 

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  14:         printf("discriptor is %d/n/n", fileno(file)); 

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  15: }

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  16: 

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  17: 

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  18: int main(int argc, char** argv)

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  19:
 
 {

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  20:         printf("stdin is ");

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  21:         streaming_property(stdin);

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  22: 

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  23:         cout << "Change BUF" << endl << endl;

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  24: 

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  25:         //修改stdin為全緩衝區，緩衝區大小為1024

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  26:         char buf[1024];

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  27:         setvbuf(stdin, buf, _IOFBF, 1024);

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  28: 

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  29:         printf("stdin is ");

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  30:         streaming_property(stdin);

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  31: 

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  32: 

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  33:         char c ; 

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  34: 

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  35:         int x = 0;

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  36: 

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  37:         //輸入為q時，退出

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  38:         while((c = getc(stdin)) != 'q')

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  39:         {

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  40: 

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  41:                 switch(c)

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  42:                 {

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  43:                 case 'A':

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  44:                         x++;

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  45:                         break;

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  46:                 case 'B':

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  47:                         cout << endl << "x = " <<  x << endl;;

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  48:                         break;

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  49:                 case 'C':

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  50:                         x--;

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  51:                         break;

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  52:                 default:

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  53:                         cout << "please input A/B/C/q" << endl;

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  54:                 }

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  55:         }

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  56: 

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  57:         return 0;

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  58: }

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  59: 

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  60: 輸出：

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  61: $ ./bin/test 

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  62: stdin is fully-buffered

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  63: buffer size is 0

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  64: discriptor is 0

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  65: 

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  66: Change BUF

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  67: 

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  68: stdin is fully-buffered

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  69: buffer size is 1024

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  70: discriptor is 0

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  71: 

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  72: AAAAAAAAAAAAAAAAAAAAABqqqqqqqqqqqqqqqqqqqqqq

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  73: 

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  74: x = 21

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  75: $

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