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authorzlg <zlg@zlg.space>2022-01-09 16:46:25 -0800
committerzlg <zlg@zlg.space>2022-01-09 16:46:25 -0800
commit41d86a29051af9e3b5fe7e37bd4c0c0a18993767 (patch)
tree185cd13f637555cd794c661d03a79b5adc261dd2
parentRefactor syscalls.h for ch8 exercises (diff)
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Solve exercise 8-3: fflush and fclose
-rw-r--r--ch8/8-03_fflush-and-fclose.c40
1 files changed, 40 insertions, 0 deletions
diff --git a/ch8/8-03_fflush-and-fclose.c b/ch8/8-03_fflush-and-fclose.c
new file mode 100644
index 0000000..add2318
--- /dev/null
+++ b/ch8/8-03_fflush-and-fclose.c
@@ -0,0 +1,40 @@
+#include <errno.h>
+#include <string.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include "syscalls.h"
+/* The C Programming Language: 2nd Edition
+ *
+ * Exercise 8-3: Design and write `_flushbuf`, `fflush`, and `fclose`.
+ *
+ * Notes: Not much guidance here, eh? :) We'll want to consult manpages.
+ *
+ * _flushbuf returns 0 on success, -1 on failure.
+ * fflush flushes a buffer, or *all* buffers
+ * fclose does housekeeping on _iob members so fds can be juggled
+ *
+ * Since work done in these exercises is predominantly in a header file, the
+ * final implementation is used for all exercises that rely on it. Attempts
+ * have been made to demonstrate *what* is being done, but it's difficult to do
+ * so without creating side effects inside the buffers themselves. Trust that
+ * if this file outputs its own source, everything is fine.
+ */
+
+int main() {
+ /* Let's copy 8-2's exercise but get a different look on the buffer. */
+ /* show the contents of buffers before and after flush */
+ FILE *fp = fopen("8-03_fflush-and-fclose.c", "r");
+ if (fp != NULL) {
+ char c;
+ while ((c = getc(fp)) != EOF) {
+ putchar(c);
+ }
+ /* fclose calls fflush */
+ fclose(fp);
+ fclose(stdout);
+ } else {
+ puts("Could not open file for reading.");
+ }
+ return 0;
+}