From f390347bb4bdab0e57543cae65701dab7200501b Mon Sep 17 00:00:00 2001
From: Wojtek Kosior <kwojtus@protonmail.com>
Date: Sun, 30 Jun 2019 21:50:10 +0200
Subject: error handling using GOTO

---
 src/main.f90 | 45 +++++++++++++++++++++++++++++++++------------
 1 file changed, 33 insertions(+), 12 deletions(-)

diff --git a/src/main.f90 b/src/main.f90
index 8c7467a..c671b8c 100644
--- a/src/main.f90
+++ b/src/main.f90
@@ -1,6 +1,7 @@
 PROGRAM integrator
   USE quadratures
   USE functions
+  USE iso_fortran_env, ONLY: error_unit
   IMPLICIT none
 
   real(kind=8) :: ibeg, iend, val
@@ -8,9 +9,14 @@ PROGRAM integrator
   procedure(integrate), pointer :: numerical_int
   procedure(funint), pointer :: fun
   procedure(analytical_integral), pointer :: analytical_int
-  character(100) :: arg
+  character(100) :: arg, errmsg
+  logical :: isok = .true.
 
-  IF (command_argument_count() < 4) STOP "4 arguments required"
+  IF (command_argument_count() < 4) THEN
+     errmsg = "at least 4 arguments required"
+     isok = .false.
+     GOTO 1
+  END IF
 
   call get_command_argument(2, arg)
 
@@ -24,7 +30,9 @@ PROGRAM integrator
      fun            => my_poly
      analytical_int => my_poly_int
   ELSE
-     STOP "bad second argument (should be 'exp', 'sin' or 'poly')"
+     errmsg =  "bad second argument (should be 'exp', 'sin' or 'poly')"
+     isok = .false.
+     GOTO 1
   END IF
 
   
@@ -44,17 +52,22 @@ PROGRAM integrator
   ELSE IF (arg == "newton-cotes") THEN
      numerical_int => newton_cotes
   ELSE IF (arg == "analytical")   THEN
-     IF (this_image() == 1) write (*,*) analytical_int(ibeg, iend)
-     STOP
+     if (this_image() == 1) write (*,*) analytical_int(ibeg, iend)
+     GOTO 1
   ELSE
-     STOP "bad first argument (should be 'gauss', 'newton-cotes'" &
-          // " or 'analytical')"
+     errmsg = "bad first argument (should be 'gauss',"            &
+          // " 'newton-cotes' or 'analytical')"
+     isok = .false.
+     GOTO 1
   END IF
 
   
-  IF (command_argument_count() < 5)                               &
-       STOP "5th argument (polynomial order) required"            &
-       // " for numerical integration"
+  IF (command_argument_count() < 5) THEN
+     errmsg = "5th argument (polynomial order) required"          &
+          // " for numerical integration"
+     isok = .false.
+     GOTO 1
+  END IF
   
   call get_command_argument(5, arg)
   read (arg,*) poly_order
@@ -63,11 +76,19 @@ PROGRAM integrator
   IF (command_argument_count() > 5) THEN
      call get_command_argument(6, arg)
      read (arg,*) subintervals
-     IF (subintervals < 1) STOP "subintervals number must be positive"
+     IF (subintervals < 1) THEN
+        errmsg = "subintervals number must be positive"
+        isok = .false.
+        GOTO 1
+     END IF
   END IF
 
   val = numerical_int(ibeg, iend, fun, poly_order)
 
-  IF (this_image() == 1) write (*,*) val
+  if (this_image() == 1) write (*,*) val
+
+  1 if (this_image() == 1 .and. .not. isok) write(*,*) trim(errmsg)
   
+CONTAINS
+
 END PROGRAM integrator
-- 
cgit v1.2.3