Data commit

Task/Determine-if-a-string-is-numeric/ALGOL-68/determine-if-a-string-is-numeric.alg

@@ -0,0 +1,26 @@
+PROC is numeric = (REF STRING string) BOOL: (
+  BOOL out := TRUE;
+  PROC call back false = (REF FILE f)BOOL: (out:= FALSE; TRUE);
+
+  FILE memory;
+  associate(memory, string);
+  on value error(memory, call back false);
+  on logical file end(memory, call back false);
+
+  UNION (INT, REAL, COMPL) numeric:=0.0;
+  # use a FORMAT pattern instead of a regular expression #
+  getf(memory, ($gl$, numeric));
+  out
+);
+
+test:(
+   STRING
+     s1 := "152",
+     s2 := "-3.1415926",
+     s3 := "Foo123";
+   print((
+     s1, " results in ", is numeric(s1), new line,
+     s2, " results in ", is numeric(s2), new line,
+     s3, " results in ", is numeric(s3), new line
+   ))
+)