From 729b54b9f6921ca9a4ee91ddb743a6fb7203658c Mon Sep 17 00:00:00 2001
From: zlg <zlg@zlg.space>
Date: Mon, 20 Feb 2017 03:21:59 -0800
Subject: Solve Exercise 7-8: Paged file print-outs

---
 ch7/7-08_print-file-pages.c | 91 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 ch7/7-08_print-file-pages.c

(limited to 'ch7')

diff --git a/ch7/7-08_print-file-pages.c b/ch7/7-08_print-file-pages.c
new file mode 100644
index 0000000..8f259b9
--- /dev/null
+++ b/ch7/7-08_print-file-pages.c
@@ -0,0 +1,91 @@
+#include <stdio.h>
+#include <string.h>
+
+/* The C Programming Language: 2nd Edition
+ *
+ * Exercise 7-8: Write a program to print a set of files, starting each new one
+ * on a new page, with a title and a running page count for each file.
+ *
+ * Notes: This could be done using functions written in exercise 7-2, but I
+ * decided to go with library functions when I could. A caveat to keep in mind
+ * on a real system is that the modern way to print some of the output is with
+ * snprintf, which doesn't exist in ANSI C. There are places where, to be safe,
+ * you should check bounds. Both line buffers are the same size here, however,
+ * so I didn't bother since I know they can hold each others' contents.
+ *
+ * If you were to do this correctly, it would be a lot like the `less` program.
+ */
+
+/* The dimensions of a "page". Using a classic size because reasons. */
+#define PAGE_WIDTH 80
+#define PAGE_HEIGHT 24
+
+int lineno = 0;
+int pageno = 0;
+FILE *fp;
+char buffer[PAGE_WIDTH];
+char line[PAGE_WIDTH];
+
+void page_break() {
+	while (lineno < (PAGE_HEIGHT - 1)) {
+		printf("\n");
+		lineno++;
+	}
+}
+
+int endswith_nl(char *s) {
+	int i;
+	for (i = 0; s[i] != '\0'; i++) {
+	}
+	if (i > 0 && s[i - 1] == '\n') {
+		return 1;
+	}
+	return 0;
+}
+
+void print_header(char *path) {
+	pageno++;
+	lineno++;
+	char *prefix = "FILE:";
+	sprintf(line, "%-*s %-*s", (int) strlen(prefix), prefix, (PAGE_WIDTH - ((int)strlen(prefix))), path);
+	printf("%s\n", line);
+}
+
+void print_footer(void) {
+	page_break();
+	sprintf(line, "Page %d\n", pageno);
+	printf("%*s", PAGE_WIDTH, line);
+	lineno = 0;
+}
+
+int main(int argc, char *argv[]) {
+	int i = 0;
+	char c;
+	while (argc > 1) {
+		i++;
+		argc--;
+		if ((fp = fopen(argv[i], "r"))) {
+			while ((c = fgetc(fp)) != EOF) {
+				ungetc(c, fp);
+				print_header(argv[i]);
+				while (fgets(buffer, PAGE_WIDTH, fp)) {
+					sprintf(line, "%s", buffer);
+					printf("%s", line);
+					if (!endswith_nl(line)) {
+						printf("\n");
+					}
+					lineno++;
+					if (lineno == (PAGE_HEIGHT - 1)) {
+						break;
+					}
+				}
+				print_footer();
+			}
+			fclose(fp);
+			pageno = 0;
+		} else {
+			printf("err: could not open file '%s' for reading.\n", argv[i]);
+		}
+	}
+	return 0;
+}
-- 
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