The check for the scale vector was not comparing the name in a case-insensitive manner, so unlet Yes would delete the default yes scale vector, for example. That issue was corrected. The code was also made more modular and descriptive regarding the check for the scale vector. Also, the warning now prints the scale vector as it is stored to make clear that vector names are not case sensitive.

src/frontend/postcoms.c

@@ -31,31 +31,49 @@ static void DelPlotWindows(struct plot *pl);
 /* check if the user want's to delete the scale vector of the current plot.
    This should not happen, because then redrawing the graph crashes ngspice */
 static bool
-check_cp(char* vecname)
+is_scale_vec_of_current_plot(const char *v_name)
 {
-    if (plot_cur && plot_cur->pl_scale && plot_cur->pl_scale->v_name && eq(plot_cur->pl_scale->v_name, vecname)) {
-        fprintf(cp_err, "\nWarning: Scale vector '%s' of current plot cannot be deleted!\n", vecname);
-        fprintf(cp_err, "    Command 'unlet %s' is ignored.\n\n", vecname);
-        return TRUE;
+    if (!plot_cur) { /* no current plot */
+        return FALSE;
     }
-    else
+
+    const struct dvec * const pl_scale = plot_cur->pl_scale;
+    if (!pl_scale) { /* no scale vector */
         return FALSE;
-}
+    }
 
+    /* Test if this vector's name matches the scale vector's name */
+    return cieq(v_name, pl_scale->v_name);
+} /* end of function is_scale_vec_of_current_plot */
+
+
+
+/* Remove vectors in the wordlist from the current plot */
 void
 com_unlet(wordlist *wl)
 {
-    while (wl) {
-        /* don't delete the scale vector of the current plot */
-        if (!check_cp(wl->wl_word))
-            vec_remove(wl->wl_word);
-        wl = wl->wl_next;
-    }
-}
+    for ( ; wl != (wordlist *) NULL; wl = wl->wl_next) {
+        /* Don't delete the scale vector of the current plot */
+        const char * const vector_name = wl->wl_word;
+        if (is_scale_vec_of_current_plot(vector_name)) {
+            /* If it is the scale vector of the current plot, print a
+             * warning. Note that if it is true,  the scale vector name must
+             * exist, so no part of plot_cur->pl_scale->v_name can be null. */
+            fprintf(cp_err,
+                    "\nWarning: Scale vector '%s' of the current plot "
+                    "cannot be deleted!\n"
+                    "Command 'unlet %s' is ignored.\n\n",
+                    plot_cur->pl_scale->v_name, vector_name);
+        }
+        else {
+            vec_remove(vector_name);
+        }
+    } /* end of loop over vectors to delete */
+} /* end of function com_unlet */
 
 
-/* Load in a file. */
 
+/* Load in a file. */
 void
 com_load(wordlist *wl)
 {
@@ -461,7 +479,7 @@ com_write(wordlist *wl)
                 /* Note that since we are building a new plot
                  * we don't want to vec_new this one...
                  */
-                tfree(vv->v_name);
+                txfree(vv->v_name);
                 vv->v_name = basename;
 
                 if (end)
@@ -512,10 +530,7 @@ com_write(wordlist *wl)
             /* Otherwise loop through again... */
         }
 
-        if (ascii)
-            raw_write(file, &newplot, appendwrite, FALSE);
-        else
-            raw_write(file, &newplot, appendwrite, TRUE);
+        raw_write(file, &newplot, appendwrite, !ascii);
 
         for (vv = newplot.pl_dvecs; vv;) {
             struct dvec *next_vv = vv->v_next;