Skip to content
New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Jump to bottom

fmt: %#g behavior not consistent #36562

Closed
musiphil opened this issue Jan 15, 2020 · 3 comments
Closed

fmt: %#g behavior not consistent #36562

musiphil opened this issue Jan 15, 2020 · 3 comments
Labels
FrozenDueToAge help wanted NeedsFix The path to resolution is known, but the work has not been done.
Milestone
Go1.15

Comments

@musiphil
Copy link

What version of Go are you using (go version)?

$ go version
go version go1.13.4 linux/amd64

Does this issue reproduce with the latest release?

Yes.

What operating system and processor architecture are you using (go env)?

go env Output
$ go env
GO111MODULE=""
GOARCH="amd64"
GOBIN=""
GOCACHE="$HOME/.cache/go-build"
GOENV="$HOME/.config/go/env"
GOEXE=""
GOFLAGS=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GONOPROXY=""
GONOSUMDB=""
GOOS="linux"
GOPATH="$HOME/go"
GOPRIVATE=""
GOPROXY="https://proxy.golang.org,direct"
GOROOT="/usr/lib/google-golang"
GOSUMDB="sum.golang.org"
GOTMPDIR=""
GOTOOLDIR="/usr/lib/google-golang/pkg/tool/linux_amd64"
GCCGO="gccgo"
AR="ar"
CC="clang"
CXX="clang++"
CGO_ENABLED="1"
GOMOD=""
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"
PKG_CONFIG="pkg-config"
GOGCCFLAGS="-fPIC -m64 -pthread -fno-caret-diagnostics -Qunused-arguments -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build990462557=/tmp/go-build -gno-record-gcc-switches"

What did you do?

https://play.golang.org/p/uhRa_BD_pUX

fmt.Printf("%#.4g\n", 1.234)
fmt.Printf("%#.4g\n", 0.1234)
fmt.Printf("%#.4g\n", 1.23)
fmt.Printf("%#.4g\n", 0.123)
fmt.Printf("%#.4g\n", 1.2)
fmt.Printf("%#.4g\n", 0.12)

What did you expect to see?

1.234
0.1234
1.230
0.1230
1.200
0.1200

%#.4g should print 4 significant digits, without removing trailing zeros.

What did you see instead?

1.234
0.1234
1.230
0.123
1.200
0.120

The trailing zero from 1.230 is erroneously removed.
@martisch
Copy link
Contributor

martisch commented Jan 15, 2020 •
edited
Loading

This seems consistent with the documentation (https://godoc.org/fmt) of the g verb and precision:

"For floating-point values, width sets the minimum width of the field and precision sets the number of places after the decimal, if appropriate, except that for %g/%G precision sets the maximum number of significant digits (trailing zeros are removed)."

@martisch martisch added the WaitingForInfo Issue is not actionable because of missing required information, which needs to be provided. label Jan 15, 2020
@martisch
Copy link
Contributor

martisch commented Jan 15, 2020 •
edited
Loading

I see now that # is supposed to alter the g verb behavior to not remove trailing zeros later in the documentation.

"do not remove trailing zeros for %g and %G;"

So you are right this should have trailing zeros.

@martisch martisch removed the WaitingForInfo Issue is not actionable because of missing required information, which needs to be provided. label Jan 15, 2020
@martisch martisch added this to the Go1.15 milestone Jan 15, 2020
@martisch martisch self-assigned this Jan 15, 2020
@martisch martisch added NeedsFix The path to resolution is known, but the work has not been done. help wanted labels Jan 15, 2020
yah01 added a commit to yah01/go that referenced this issue Jan 15, 2020
@yah01
fixes golang#36562
ca6628b
@yah01 yah01 mentioned this issue Jan 15, 2020
Closed
@gopherbot
Copy link
Contributor

Change https://golang.org/cl/215001 mentions this issue: fmt: do not remove trailing zeros for %g and %G with #(sharp) flag

yah01 added a commit to yah01/go that referenced this issue Jan 16, 2020
@yah01
fix golang#36562
586da2c
yah01 added a commit to yah01/go that referenced this issue Jan 18, 2020
@yah01
fix golang#36562
6768429
yah01 added a commit to yah01/go that referenced this issue Jan 18, 2020
@yah01
fixes golang#36562
6e1f2b6
@martisch martisch removed their assignment Jan 18, 2020
@golang golang locked and limited conversation to collaborators Feb 25, 2021
Sign up for free to subscribe to this conversation on GitHub. Already have an account? Sign in.
Assignees
No one assigned
Labels
FrozenDueToAge help wanted NeedsFix The path to resolution is known, but the work has not been done.
Projects
None yet
Milestone
Go1.15
Development

Successfully merging a pull request may close this issue.

fmt: do not remove trailing zeros for %g and %G with #(sharp) flag yah01/go
3 participants
@martisch @musiphil @gopherbot