strconv: document parsing of leading +/-
Explicitly document the handling of a sign prefix, and the interaction
between the sign and base prefixes.
Fixes #46641.
Change-Id: I3cd6773e3f074fe671a944a05a79d2408137fcd4
Reviewed-on: https://go-review.googlesource.com/c/go/+/325875
Trust: Damien Neil <dneil@google.com>
Run-TryBot: Damien Neil <dneil@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Rob Pike <r@golang.org>
diff --git a/src/strconv/atoi.go b/src/strconv/atoi.go
index c9ba038..631b487 100644
--- a/src/strconv/atoi.go
+++ b/src/strconv/atoi.go
@@ -57,6 +57,8 @@
const maxUint64 = 1<<64 - 1
// ParseUint is like ParseInt but for unsigned numbers.
+//
+// A sign prefix is not permitted.
func ParseUint(s string, base int, bitSize int) (uint64, error) {
const fnParseUint = "ParseUint"
@@ -159,10 +161,13 @@
// ParseInt interprets a string s in the given base (0, 2 to 36) and
// bit size (0 to 64) and returns the corresponding value i.
//
+// The string may begin with a leading sign: "+" or "-".
+//
// If the base argument is 0, the true base is implied by the string's
-// prefix: 2 for "0b", 8 for "0" or "0o", 16 for "0x", and 10 otherwise.
-// Also, for argument base 0 only, underscore characters are permitted
-// as defined by the Go syntax for integer literals.
+// prefix following the sign (if present): 2 for "0b", 8 for "0" or "0o",
+// 16 for "0x", and 10 otherwise. Also, for argument base 0 only,
+// underscore characters are permitted as defined by the Go syntax for
+// integer literals.
//
// The bitSize argument specifies the integer type
// that the result must fit into. Bit sizes 0, 8, 16, 32, and 64
diff --git a/src/strconv/atoi_test.go b/src/strconv/atoi_test.go
index 178fb01..867fa66 100644
--- a/src/strconv/atoi_test.go
+++ b/src/strconv/atoi_test.go
@@ -33,6 +33,9 @@
{"_12345", 0, ErrSyntax},
{"1__2345", 0, ErrSyntax},
{"12345_", 0, ErrSyntax},
+ {"-0", 0, ErrSyntax},
+ {"-1", 0, ErrSyntax},
+ {"+1", 0, ErrSyntax},
}
type parseUint64BaseTest struct {
@@ -140,8 +143,10 @@
{"", 0, ErrSyntax},
{"0", 0, nil},
{"-0", 0, nil},
+ {"+0", 0, nil},
{"1", 1, nil},
{"-1", -1, nil},
+ {"+1", 1, nil},
{"12345", 12345, nil},
{"-12345", -12345, nil},
{"012345", 12345, nil},
@@ -236,6 +241,11 @@
{"0__12345", 0, 0, ErrSyntax},
{"01234__5", 0, 0, ErrSyntax},
{"012345_", 0, 0, ErrSyntax},
+
+ {"+0xf", 0, 0xf, nil},
+ {"-0xf", 0, -0xf, nil},
+ {"0x+f", 0, 0, ErrSyntax},
+ {"0x-f", 0, 0, ErrSyntax},
}
type parseUint32Test struct {
