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strconv: fix %.2g, 40

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Fixes #845.

R=rsc
CC=golang-dev
https://golang.org/cl/1673049
This commit is contained in:
Rob Pike 2010-06-29 16:39:17 -07:00
parent 1246ad8390
commit 21f8ae8fec
2 changed files with 21 additions and 4 deletions
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14
src/pkg/strconv/ftoa.go
View File

@ -154,21 +154,27 @@ func genericFtoa(bits uint64, fmt byte, prec int, flt *floatInfo) string {
case 'f': case 'f':
return fmtF(neg, d, prec) return fmtF(neg, d, prec)
case 'g', 'G': case 'g', 'G':
// trailing zeros are removed. // trailing fractional zeros in 'e' form will be trimmed.
if prec > d.nd { eprec := prec
prec = d.nd if eprec > d.nd && d.nd >= d.dp {
eprec = d.nd
} }
// %e is used if the exponent from the conversion // %e is used if the exponent from the conversion
// is less than -4 or greater than or equal to the precision. // is less than -4 or greater than or equal to the precision.
// if precision was the shortest possible, use precision 6 for this decision. // if precision was the shortest possible, use precision 6 for this decision.
eprec := prec
if shortest { if shortest {
eprec = 6 eprec = 6
} }
exp := d.dp - 1 exp := d.dp - 1
if exp < -4 || exp >= eprec { if exp < -4 || exp >= eprec {
if prec > d.nd {
prec = d.nd
}
return fmtE(neg, d, prec-1, fmt+'e'-'g') return fmtE(neg, d, prec-1, fmt+'e'-'g')
} }
if prec > d.dp {
prec = d.nd
}
return fmtF(neg, d, max(prec-d.dp, 0)) return fmtF(neg, d, max(prec-d.dp, 0))
} }

11
src/pkg/strconv/ftoa_test.go
View File

@ -34,6 +34,17 @@ var ftoatests = []ftoaTest{
ftoaTest{200000, 'g', -1, "200000"}, ftoaTest{200000, 'g', -1, "200000"},
ftoaTest{2000000, 'g', -1, "2e+06"}, ftoaTest{2000000, 'g', -1, "2e+06"},
// g conversion and zero suppression
ftoaTest{400, 'g', 2, "4e+02"},
ftoaTest{40, 'g', 2, "40"},
ftoaTest{4, 'g', 2, "4"},
ftoaTest{.4, 'g', 2, "0.4"},
ftoaTest{.04, 'g', 2, "0.04"},
ftoaTest{.004, 'g', 2, "0.004"},
ftoaTest{.0004, 'g', 2, "0.0004"},
ftoaTest{.00004, 'g', 2, "4e-05"},
ftoaTest{.000004, 'g', 2, "4e-06"},
ftoaTest{0, 'e', 5, "0.00000e+00"}, ftoaTest{0, 'e', 5, "0.00000e+00"},
ftoaTest{0, 'f', 5, "0.00000"}, ftoaTest{0, 'f', 5, "0.00000"},
ftoaTest{0, 'g', 5, "0"}, ftoaTest{0, 'g', 5, "0"},