aboutsummaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--1-20_detab.c43
1 files changed, 43 insertions, 0 deletions
diff --git a/1-20_detab.c b/1-20_detab.c
new file mode 100644
index 0000000..3101610
--- /dev/null
+++ b/1-20_detab.c
@@ -0,0 +1,43 @@
+#include <stdio.h>
+
+/* The C Programming Language: 2nd Edition
+ * Exercise 1-20:
+ * "Write a program `detab` that replaces tabs in the input with the proper
+ * number of blanks to space to the next tabstop. Assume a fixed set of
+ * tabstops, say every 'n' columns. Should 'n' be a variable or a symbolic
+ * parameter?
+ *
+ * Answer: 'n' should be a symbolic parameter. It's more apparent what's being
+ * worked with and it's not susceptible to scope. Though, in this simple
+ * program it really doesn't matter.
+ */
+
+#define TABWIDTH 8
+
+int main(void) {
+ int column, c;
+ column = 0;
+ while ((c = getchar()) != EOF) {
+ // Be sure that the character is a tab
+ if (c == '\t') {
+ /*
+ * Divide a line by TABWIDTH and you have your tabstops. If you
+ * modulo by TABWIDTH and it equals 0, you've reached a tabstop and
+ * don't need to output more spaces!
+ */
+ while (column % TABWIDTH != 0 && column != 0) {
+ putchar(' ');
+ ++column;
+ }
+ } else {
+ // non-tabs simply get output.
+ putchar(c);
+ ++column;
+ // Line-endings should reset the column counter after being output.
+ if (c == '\n') {
+ column = 0;
+ }
+ }
+ }
+ return 0;
+}