fix issues with examples in strings

Author: jvdp1

test/example/strings/example_padl.f90

@@ -7,7 +7,7 @@ program example_padl
   string = "left pad this string"
 ! string <-- "left pad this string"
 
-  print '(a)', padl(string, 25, "$") ! "$$$$$left pad this string"
+  print '(dt)', padl(string, 25, "$") ! "$$$$$left pad this string"
 
   string = padl(string, 25)
 ! string <-- "     left pad this string"

test/example/strings/example_padr.f90

@@ -7,7 +7,7 @@ program example_padr
   string = "right pad this string"
 ! string <-- "right pad this string"
 
-  print '(a)', padr(string, 25, "$") ! "right pad this string$$$$"
+  print '(dt)', padr(string, 25, "$") ! "right pad this string$$$$"
 
   string = padr(string, 25)
 ! string <-- "right pad this string    "

test/example/strings/example_replace_all.f90

@@ -7,7 +7,7 @@ program example_replace_all
   string = "hurdles here, hurdles there, hurdles everywhere"
 ! string <-- "hurdles here, hurdles there, hurdles everywhere"
 
-  print'(a)', replace_all(string, "hurdles", "learn from")
+  print'(dt)', replace_all(string, "hurdles", "learn from")
 ! "learn from here, learn from there, learn from everywhere"
 
   string = replace_all(string, "hurdles", "technology")