Data commit

Task/Determine-if-a-string-is-numeric/BBC-BASIC/determine-if-a-string-is-numeric.basic

@@ -0,0 +1,19 @@
+      REPEAT
+        READ N$
+        IF FN_isanumber(N$) THEN
+          PRINT "'" N$ "' is a number"
+        ELSE
+          PRINT "'" N$ "' is NOT a number"
+        ENDIF
+      UNTIL N$ = "end"
+      END
+
+      DATA "PI", "0123", "-0123", "12.30", "-12.30", "123!", "0"
+      DATA "0.0", ".123", "-.123", "12E3", "12E-3", "12+3", "end"
+
+      DEF FN_isanumber(A$)
+      ON ERROR LOCAL = FALSE
+      IF EVAL("(" + A$ + ")") <> VAL(A$) THEN = FALSE
+      IF VAL(A$) <> 0 THEN = TRUE
+      IF LEFT$(A$,1) = "0" THEN = TRUE
+      = FALSE