ch5: 5.11.c renamed all chapter from 'chr' to 'ch'

ch5/5.11.c

@@ -0,0 +1,93 @@
+/*
+ * Exercise 5-11. Modify the program entab and detab (written as exercises in
+ * Chapter 1) to accept a list of tab stops as arguments. Use the default tab
+ * settings if there are no arguments.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+
+#define MAXLEN 1000
+#define TABLEN 8
+
+int getLine(char line[], int maxlen) {
+  int i, c;
+
+  for (i = 0; i < maxlen - 1 && ((c = getchar()) != EOF) && c != '\n'; ++i)
+    line[i] = c;
+  if (c == '\n') {
+    line[i] = c;
+    ++i;
+  }
+  line[i] = '\0';
+
+  return i;
+}
+
+// replace tabs with spaces
+void detab(char in[], char out[], int argc, char *argv[]) {
+  int i, j, k = 1;
+  unsigned int snr;
+
+  for (i = j = 0; in[i] != '\0'; ++i) {
+    if (in[i] == '\t') {
+      if (argc > 1 && k < argc) {
+        snr = atoi(argv[k]) - j % atoi(argv[k]);
+        k++;
+      } else {
+        snr = TABLEN - j % TABLEN;
+      }
+      while (snr) {
+        out[j++] = ' ';
+        --snr;
+      }
+    } else {
+      out[j++] = in[i];
+    }
+  }
+  out[j] = '\0';
+}
+
+// replace strings of blanks by the min number of tabs and blanks
+void entab(char in[], char out[], int argc, char *argv[]) {
+  int i, j, k = 1;
+  int nblanks, ntabs;
+
+  for (i = j = 0; in[i] != '\0'; ++i) {
+    if (in[i] == ' ') {
+      for (nblanks = ntabs = 0; in[i] == ' '; ++i) {
+        if (argc > 1 && k < argc) {
+          if ((nblanks + 1) % atoi(argv[k]) == 0) {
+            ++ntabs;
+            nblanks = 0;
+            ++k;
+          }
+        } else if ((nblanks + 1) % TABLEN == 0) {
+          ++ntabs;
+          nblanks = 0;
+        } else
+          ++nblanks;
+      }
+      --i;
+      while (ntabs-- > 0)
+        out[j++] = '\t';
+      while (nblanks-- > 0)
+        out[j++] = ' ';
+    } else
+      out[j++] = in[i];
+  }
+  out[j] = '\0';
+}
+
+int main(int argc, char *argv[]) {
+  char in[MAXLEN];
+  char out[MAXLEN];
+
+  while ((getLine(in, MAXLEN)) > 0) {
+    entab(in, out, argc, argv);
+    printf("%s", out);
+    detab(in, out, argc, argv);
+    printf("%s", out);
+  }
+
+  return 0;
+}