Update Exercises.rst

Made a fix to the code answer for count(p) ex_8_3. Prior to the fix, if the answer is copied and pasted into the Question tab and run, it fails due to two issues (divide by 0 when p is the empty string and not returning any answer).

Author: psmaker

_sources/Strings/Exercises.rst

@@ -156,9 +156,12 @@ Exercises
                         if achar == 'e':
                             numberOfe = numberOfe + 1
 
-                percent_with_e = (numberOfe / totalChars) * 100
-                print("Your text contains", totalChars, "alphabetic characters of which", numberOfe, "(", percent_with_e, "%)", "are 'e'.")
-
+                if totalChars != 0:
+                    percent_with_e = (numberOfe / totalChars) * 100
+                    print("Your text contains", totalChars, "alphabetic characters of which", numberOfe, "(", percent_with_e, "%)", "are 'e'.")
+                else:
+                    print("There were no characters in the input string p")
+                return (numberOfe)
 
             p = '''
             "If the automobile had followed the same development cycle as the computer, a