read character: automatically truncate to c_null_char if present

Author: scivision

VERSION

@@ -1 +1 @@
-1.4.3
+1.4.4

src/reader.in.f90

@@ -1,12 +1,14 @@
 submodule (nc4fortran:read) reader
 !! This submodule is for reading 0-D..7-D data
 
+use, intrinsic :: iso_c_binding, only : c_null_char
 implicit none (type, external)
 
 contains
 
 module procedure nc_read_scalar
-integer :: varid, ier
+integer :: varid, ier, i
+integer, allocatable :: dims(:)
 
 if(.not.self%is_open) error stop 'nc4fortran:reader file handle not open'
 
@@ -17,15 +19,14 @@
 type is (character(*))
   !! NetCDF4 requires knowing the exact character length as if it were an array without fill values
   !! HDF5 is not this strict; having a longer string variable than disk variable is OK in HDF5, but not NetCDF4
-  charshape : block
-    integer, allocatable :: dims(:)
-    call self%shape(dname, dims)
-    charbuf : block
-      character(len=dims(1)) :: buf
-      ier = nf90_get_var(self%ncid, varid, buf)
-      value = buf
-    end block charbuf
-  end block charshape
+  call self%shape(dname, dims)
+  charbuf : block
+    character(len=dims(1)) :: buf
+    ier = nf90_get_var(self%ncid, varid, buf)
+    i = index(buf, c_null_char) - 1
+    if(i == -1) i = len_trim(buf)
+    value = buf(:i)
+  end block charbuf
 type is (real(real64))
   ier = nf90_get_var(self%ncid, varid, value)
 type is (real(real32))

src/tests/test_string.f90

@@ -12,8 +12,6 @@ program test_string
 
 character(2) :: value
 character(1024) :: val1k
-character(:), allocatable :: final
-integer :: i
 character(*), parameter :: path='test_string.nc'
 
 call h%open(path, action='w')
@@ -26,23 +24,19 @@ program test_string
 call h%open(path, action='r')
 call h%read('little', value)
 
-if (value /= '42') then
-  write(stderr,*) 'test_string:  read/write verification failure. Value: '// value
-  error stop
-endif
+if (value /= '42') error stop 'test_string:  read/write verification failure. Value: '// value
 
 print *,'test_string_rw: reading too much data'
 !! try reading too much data, then truncating to first C_NULL
 call h%read('little', val1k)
-i = index(val1k, c_null_char)
-final = val1k(:i-1)
 
-if (len(final) /= 2) then
-  write(stderr, *) 'trimming str to c_null did not work, got len() = ', len(final)
-  write(stderr, *) iachar(final(3:3))
+if (len_trim(val1k) /= 2) then
+  write(stderr, *) 'expected len_trim 2, got len_trim = ', len(val1k)
   error stop
 endif
 
 call h%close()
 
+print *, 'OK: test_string'
+
 end program