Merge pull request #14377 from sarvjeetsinghghotra/issue-14291

RFC: Modified writedlm() to write leading zeros when writing floats #14291

Author: jakebolewski

base/grisu.jl

@@ -127,7 +127,7 @@ Base.showcompact(io::IO, x::Float16) = _show(io, x, PRECISION, 5, false)
 
 # normal:
 #   0 < pt < len        ####.####           len+1
-#   pt <= 0             .000########        len-pt+1
+#   pt <= 0             0.000########       len-pt+1
 #   len <= pt (dot)     ########000.        pt+1
 #   len <= pt (no dot)  ########000         pt
 # exponential:
@@ -149,8 +149,8 @@ function _print_shortest(io::IO, x::AbstractFloat, dot::Bool, mode, n::Int)
         write(io, dec(e))
         return
     elseif pt <= 0
-        # => .000########
-        write(io, '.')
+        # => 0.000########
+        write(io, "0.")
         while pt < 0
             write(io, '0')
             pt += 1

test/datafmt.jl

@@ -93,6 +93,18 @@ let x = [1,2,3], y = [4,5,6], io = IOBuffer()
     @test readcsv(io) == [x y]
 end
 
+let x = [0.1 0.3 0.5], io = IOBuffer()
+    writedlm(io, x, ", ")
+    seek(io, 0)
+    @test readall(io) == "0.1, 0.3, 0.5\n"
+end
+
+let x = [0.1 0.3 0.5], io = IOBuffer()
+    writedlm(io, x, ", ")
+    seek(io, 0)
+    @test readcsv(io) == [0.1 0.3 0.5]
+end
+
 let x = ["abc", "def\"ghi", "jk\nl"], y = [1, ",", "\"quoted\""], io = IOBuffer()
     writedlm(io, zip(x,y), ',')
     seek(io, 0)