28 Text processing library [text]

28.5 Formatting [format]

28.5.2 Format string [format.string]

28.5.2.2 Standard format specifiers [format.string.std]

Table 105 — Meaning of sign options [tab:format.sign]
🔗
Option
Meaning
🔗
+
Indicates that a sign should be used for both non-negative and negative numbers.
The + sign is inserted before the output of to_chars for non-negative numbers other than negative zero.
[Note 5: 
For negative numbers and negative zero the output of to_chars will already contain the sign so no additional transformation is performed.
— end note]
🔗
-
Indicates that a sign should be used for negative numbers and negative zero only (this is the default behavior).
🔗
space
Indicates that a leading space should be used for non-negative numbers other than negative zero, and a minus sign for negative numbers and negative zero.