diff options
Diffstat (limited to 'src/fmt')
| -rw-r--r-- | src/fmt/doc.go | 20 | ||||
| -rw-r--r-- | src/fmt/fmt_test.go | 7 | ||||
| -rw-r--r-- | src/fmt/format.go | 6 |
3 files changed, 25 insertions, 8 deletions
diff --git a/src/fmt/doc.go b/src/fmt/doc.go index b7eaedc11..00dd8d01c 100644 --- a/src/fmt/doc.go +++ b/src/fmt/doc.go @@ -63,16 +63,20 @@ %9.2f width 9, precision 2 %9.f width 9, precision 0 - Width and precision are measured in units of Unicode code points. - (This differs from C's printf where the units are numbers - of bytes.) Either or both of the flags may be replaced with the - character '*', causing their values to be obtained from the next - operand, which must be of type int. + Width and precision are measured in units of Unicode code points, + that is, runes. (This differs from C's printf where the + units are always measured in bytes.) Either or both of the flags + may be replaced with the character '*', causing their values to be + obtained from the next operand, which must be of type int. - For most values, width is the minimum number of characters to output, + For most values, width is the minimum number of runes to output, padding the formatted form with spaces if necessary. - For strings, precision is the maximum number of characters to output, - truncating if necessary. + + For strings, byte slices and byte arrays, however, precision + limits the length of the input to be formatted (not the size of + the output), truncating if necessary. Normally it is measured in + runes, but for these types when formatted with the %x or %X format + it is measured in bytes. For floating-point values, width sets the minimum width of the field and precision sets the number of places after the decimal, if appropriate, diff --git a/src/fmt/fmt_test.go b/src/fmt/fmt_test.go index cca0a495f..4586fcf93 100644 --- a/src/fmt/fmt_test.go +++ b/src/fmt/fmt_test.go @@ -194,8 +194,15 @@ var fmtTests = []struct { {"%.5s", "日本語日本語", "日本語日本"}, {"%.5s", []byte("日本語日本語"), "日本語日本"}, {"%.5q", "abcdefghijklmnopqrstuvwxyz", `"abcde"`}, + {"%.5x", "abcdefghijklmnopqrstuvwxyz", `6162636465`}, + {"%.5q", []byte("abcdefghijklmnopqrstuvwxyz"), `"abcde"`}, + {"%.5x", []byte("abcdefghijklmnopqrstuvwxyz"), `6162636465`}, {"%.3q", "日本語日本語", `"日本語"`}, {"%.3q", []byte("日本語日本語"), `"日本語"`}, + {"%.1q", "日本語", `"日"`}, + {"%.1q", []byte("日本語"), `"日"`}, + {"%.1x", "日本語", `e6`}, + {"%.1X", []byte("日本語"), `E6`}, {"%10.1q", "日本語日本語", ` "日"`}, {"%3c", '⌘', " ⌘"}, {"%5q", '\u2026', ` '…'`}, diff --git a/src/fmt/format.go b/src/fmt/format.go index 255167c8f..a92f3c2f8 100644 --- a/src/fmt/format.go +++ b/src/fmt/format.go @@ -340,11 +340,17 @@ func (f *fmt) fmt_sbx(s string, b []byte, digits string) { // fmt_sx formats a string as a hexadecimal encoding of its bytes. func (f *fmt) fmt_sx(s, digits string) { + if f.precPresent && f.prec < len(s) { + s = s[:f.prec] + } f.fmt_sbx(s, nil, digits) } // fmt_bx formats a byte slice as a hexadecimal encoding of its bytes. func (f *fmt) fmt_bx(b []byte, digits string) { + if f.precPresent && f.prec < len(b) { + b = b[:f.prec] + } f.fmt_sbx("", b, digits) } |