+<sect1>Specifying file types for fopen<p>
+
+<descrip>
+
+ <tag>Explanation of File Types</tag>
+
+ ProDOS associates a file type and an auxiliary type with each file.
+ These type specifications are separate from the file's name, unlike
+ Windows which uses the file name's suffix (a.k.a.
+ extension) to specify the file type. For example, <tt/.exe/,
+ <tt/.doc/, or <tt/.bat/.
+ The ProDOS low-level
+ Machine-Language Interface (MLI) functions for creating and opening
+ files require these types to be specified. And if they don't match
+ with the file being opened, the operation may fail.
+
+ In contrast, the ISO C function <tt/fopen()/ and the POSIX function
+ <tt/open()/ have no parameter to specify either a file type or an
+ auxiliary type. Therefore, some additional mechanism for specifying
+ the file types is needed.
+
+ <tag>Specifying the File Type and Auxiliary Type</tag>
+
+ There are two global variables provided that allow the file type
+ and auxiliary type to be specified before a call to <tt/fopen()/
+ or <tt/open()/. They are defined in <tt/apple2_filetype.h/:
+
+ <tscreen>
+ <verb>
+ extern unsigned char _filetype; /* Default: PRODOS_T_BIN */
+ extern unsigned int _auxtype; /* Default: 0 */
+ </verb>
+ </tscreen>
+
+ The header file <tt/apple2_filetype.h/ also defines many values
+ that can be used to set these variables. It is included in
+ <tt/apple2.h/, which is in turn included in <tt/apple2enh.h/.
+ So it isn't necessary to include it directly. Just
+ include one of <tt/apple2.h/ or <tt/apple2enh.h/.
+
+ <tag>Example</tag>
+
+ A text file cannot be created with just the
+ standard C functions because they default to the binary type
+ <tt/PRODOS_T_BIN/. The <tt/_filetype/ variable must be set to
+ <tt/PRODOS_T_TXT/ to create a text file.
+
+ For a text file,
+ <tt/_auxtype/ specifies the record length. A zero record
+ length text file is referred to as a sequential text file.
+ This is equivalent to text files on
+ other operating systems, except that the line terminator is a
+ carriage return instead of a line-feed (Linux/BSD/MacOS) or
+ carriage return, line-feed pair (Windows).
+
+ The "sequential" text file terminology is in contrast to a
+ "random-access" text file which would
+ have a fixed-length, non-zero record length, so that the
+ file position of any individual record can be calculated.
+
+ For this example, the
+ <tt/_auxtype/ does not need to be set because it defaults to
+ the desired value, which is zero. To be more explicit,
+ <tt/_auxtype/ can also be set to <tt/PRODOS_AUX_T_TXT_SEQ/
+ which is defined as zero.
+
+ <tscreen>
+ <verb>
+ #include <stdio.h>
+ #include <string.h>
+ #include <errno.h>
+ #include <apple2.h>
+
+ void main(void)
+ {
+ FILE *out;
+ char *name = "MY.FAVS";
+
+ /*-----------------------------*/
+
+ _filetype = PRODOS_T_TXT;
+ _auxtype = PRODOS_AUX_T_TXT_SEQ;
+
+ /*-----------------------------*/
+
+ if ((out = fopen(name, "w")) != NULL) {
+ fputs("Jorah Mormont\r", out);
+ fputs("Brienne of Tarth\r", out);
+ fputs("Daenerys Targaryen\r", out);
+ fputs("Sandor Clegane\r", out);
+ if (fclose(out) == EOF) {
+ fprintf(stderr, "fclose failed for %s: %s", name, strerror(errno));
+ }
+ }
+ else {
+ fprintf(stderr, "fopen failed for %s: %s", name, strerror(errno));
+ }
+ }
+ </verb>
+ </tscreen>
+
+</descrip><p>
+
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