1 files changed, 40 insertions, 0 deletions
diff --git a/ch01/ex20-detab.c b/ch01/ex20-detab.c
new file mode 100644
index 0000000..78aae5a
--- /dev/null
+++ b/ch01/ex20-detab.c
@@ -0,0 +1,40 @@
+#include <stdio.h>
+
+#define TABSTOP 8  /* number of columns between tab stops */
+
+void putspace(int len);
+
+
+/* replace tabs with proper spaces */
+int main()
+{
+    int c;
+    int col;
+    int nspace;
+
+    col = 0;
+    while ((c = getchar()) != EOF) {
+        if (c == '\t') {
+            nspace = TABSTOP - (col % TABSTOP);
+            col = col + nspace;
+            putspace(nspace);
+        } else if (c == '\n') {
+            col = 0;
+            putchar(c);
+        } else {
+            ++col;
+            putchar(c);
+        }
+    }
+
+    return 0;
+}
+
+/* print len spaces */
+void putspace(int len)
+{
+    int i;
+
+    for (i = 0; i < len; ++i)
+        putchar(' ');
+}