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fdopen()                  STDIO Function                 fdopen()




Open a stream for standard I/O

#include <stdio.h>
FILE *fdopen(fd, type) int fd; char *type;

fdopen allocates and returns a FILE structure, or stream, for the
file descriptor  fd, as obtained from open,  creat, dup, or pipe.
type is the manner in which you want fd to be opened, as follows:


             r       Read a file
             w       Write into a file
             a       Append onto a file


***** Example *****

The following  example obtains a  file descriptor with  open, and
then uses fdopen to build a pointer to the FILE structure.


#include <ctype.h>
#include <stdio.h>



void adios(message)
char *message;
{
        fprintf(stderr, "%s\n", message);
        exit(1);
}



main(argc, argv)
int argc; char *argv[];
{
        extern FILE *fdopen();
        FILE *fp;
        int fd;
        int holder;



        if (--argc != 1)
                adios("Usage: example filename");









COHERENT Lexicon                                           Page 1

fdopen()                  STDIO Function                 fdopen()



        if ((fd = open(argv[1], 0)) == -1)
                adios("open failed.");
        if ((fp = fdopen(fd, "r")) == NULL)
                adios("fdopen failed.");



        while ((holder = fgetc(fp)) != EOF) {
                if ((holder > '\177') && (holder < ' '))
                        switch(holder) {
                        case '\t':
                        case '\n':
                                break;
                        default:
                                fprintf(stderr, "Seeing char %d\n", holder);
                                exit(1);
                        }
                fputc(holder, stdout);
        }
}


***** See Also *****

creat(), dup(), fopen(), open(), STDIO

***** Diagnostics *****

fdopen returns NULL if it cannot allocate a FILE structure.  Cur-
rently, only 20 FILE structures can be allocated per program, in-
cluding stdin, stdout, and stderr.


























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