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 type options for floating-point types [tab:format.type.float]
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Type
Meaning
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a
If precision is specified, equivalent to to_chars(first, last, value, chars_format::hex, precision) where precision is the specified formatting precision; equivalent to to_chars(first, last, value, chars_format::hex) otherwise.
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A
The same as a, except that it uses uppercase letters for digits above 9 and P to indicate the exponent.
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e
Equivalent to to_chars(first, last, value, chars_format::scientific, precision) where precision is the specified formatting precision, or 6 if precision is not specified.
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E
The same as e, except that it uses E to indicate exponent.
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f, F
Equivalent to to_chars(first, last, value, chars_format::fixed, precision) where precision is the specified formatting precision, or 6 if precision is not specified.
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g
Equivalent to to_chars(first, last, value, chars_format::general, precision) where precision is the specified formatting precision, or 6 if precision is not specified.
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G
The same as g, except that it uses E to indicate exponent.
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none
If precision is specified, equivalent to to_chars(first, last, value, chars_format::general, precision) where precision is the specified formatting precision; equivalent to to_chars(first, last, value) otherwise.