如何让Flex分析指定文本？
最近在研究flex.bison，但通常情况下只看到两种解析文本的方法，一种是直接调用yyparse分析控制台输入的数据，另外一种是打开文件后放入yyin变量，不知道可不可以直接分析我指定的一段文本？请各位赐教了
[解决办法]
Example 1
/* PIPE.C: This program uses the _pipe function to pass streams of
* text to spawned processes.
*/
#include <stdlib.h>
#include <stdio.h>
#include <io.h>
#include <fcntl.h>
#include <process.h>
#include <math.h>
enum PIPES { READ, WRITE }; /* Constants 0 and 1 for READ and WRITE */
#define NUMPROBLEM 8
void main( int argc, char *argv[] )
{
int hpipe[2];
char hstr[20];
int pid, problem, c;
int termstat;
/* If no arguments, this is the spawning process */
if( argc == 1 )
{
setvbuf( stdout, NULL, _IONBF, 0 );
/* Open a set of pipes */
if( _pipe( hpipe, 256, O_BINARY ) == -1 )
exit( 1 );
/* Convert pipe read handle to string and pass as argument
* to spawned program. Program spawns itself (argv[0]).
*/
itoa( hpipe[READ], hstr, 10 );
if( ( pid = spawnl( P_NOWAIT, argv[0], argv[0],
hstr, NULL ) ) == -1 )
printf( "Spawn failed" );
/* Put problem in write pipe. Since spawned program is
* running simultaneously, first solutions may be done
* before last problem is given.
*/
for( problem = 1000; problem <= NUMPROBLEM * 1000; problem += 1000)
{
printf( "Son, what is the square root of %d?\n", problem );
write( hpipe[WRITE], (char *)&problem, sizeof( int ) );
}
/* Wait until spawned program is done processing. */
_cwait( &termstat, pid, WAIT_CHILD );
if( termstat & 0x0 )
printf( "Child failed\n" );
close( hpipe[READ] );
close( hpipe[WRITE] );
}
/* If there is an argument, this must be the spawned process. */
else
{
/* Convert passed string handle to integer handle. */
hpipe[READ] = atoi( argv[1] );
/* Read problem from pipe and calculate solution. */
for( c = 0; c < NUMPROBLEM; c++ )
{
read( hpipe[READ], (char *)&problem, sizeof( int ) );
printf( "Dad, the square root of %d is %3.2f.\n",
problem, sqrt( ( double )problem ) );
}
}
}
Output
Son, what is the square root of 1000?
Son, what is the square root of 2000?
Son, what is the square root of 3000?
Son, what is the square root of 4000?
Son, what is the square root of 5000?
Son, what is the square root of 6000?
Son, what is the square root of 7000?
Son, what is the square root of 8000?
Dad, the square root of 1000 is 31.62.
Dad, the square root of 2000 is 44.72.
Dad, the square root of 3000 is 54.77.
Dad, the square root of 4000 is 63.25.
Dad, the square root of 5000 is 70.71.
Dad, the square root of 6000 is 77.46.
Dad, the square root of 7000 is 83.67.
Dad, the square root of 8000 is 89.44.
#undef YY_INPUT
#define YY_INPUT(buf, retval, maxlen) { retval = GetInput(buf, maxlen); }
