HP C/iX Library Reference Manual (30026-90004)

ManualsBrandsHP ManualsSoftwareMPE/iX 7.5 Operating System

261

262

263

264

265

266

267

268

269

270

310 Chapter5

HP C/iX Library Function Descriptions

setvbuf

identical:

setvbuf(fp, NULL, _IONBF, 0)

setbuf(fp, NULL)

When

type

is _IOFBF or _IOLBF, buffering for

stream

is determined by

buffer

and

size.

buffer

is not the null pointer, it must point to a character array of

size

bytes. All

buffering of

stream

is then handled through this array.

…

FILE *fp;

char buffer [256]

char *filename;

int retcode;

fp=fopen(filename, "w");

retcode=setvbuf(fp, buffer, _IOFBF, 256);

if (retcode !=0) error ();

This fragment causes stream fp to be buffered through the 256-byte array

buffer.

Serious run-time errors can occur if the buffer array is not the size speciﬁed in the call to

setvbuf() (here 256 bytes). As with setbuf, it is dangerous to use an automatic array for

the buffer. Note that the return value of setvbuf() can be used to verify that the request

was completed successfully.

…

FILE * fp;

char * filename;

int retcode;

…

fp = fopen(filename, "rt")

retcode=setvbuf(fp, NULL, _IOFBF, 2048);

if(retcode !=0) error( );

This fragment buffers stream fp through a 2048-byte buffer that is allocated by the

system.