# std::vprint_nonunicode(std::ostream)

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< cpp‎ | io‎ | basic ostream

Defined in header `<ostream>` |  |
void vprint_nonunicode( std::ostream & os, std::string_view fmt, std::format_args args ); |  | (since C++23)

Behaves as FormattedOutputFunction (except that some details of error reporting differ):

- First, constructs and checks the sentry object.
- Then, initializes an automatic variable as if by std::string out = std::vformat (os.getloc(), fmt, args);.
- Finally, inserts the character sequence `[out.begin(), out.end())` into os.

### Parameters

os | - | output stream to insert data into

fmt

-

an object that represents the format string. The format string consists of

- ordinary characters (except { and }), which are copied unchanged to the output,
- escape sequences {{ and }}, which are replaced with { and } respectively in the output, and
- replacement fields.

Each replacement field has the following format:

`{` arg-id (optional) `}` | (1) |
`{` arg-id (optional) `:` format-spec `}` | (2) |

1) replacement field without a format specification
2) replacement field with a format specification

arg-id | - | specifies the index of the argument in `args` whose value is to be used for formatting; if it is omitted, the arguments are used in order. The arg-id﻿s in a format string must all be present or all be omitted. Mixing manual and automatic indexing is an error.
format-spec | - | the format specification defined by the std::formatter specialization for the corresponding argument. Cannot start with }.

- For basic types and standard string types, the format specification is interpreted as standard format specification.
- For chrono types, the format specification is interpreted as chrono format specification.

- For range types, the format specification is interpreted as range format specification.
- For std::pair and std::tuple, the format specification is interpreted as tuple format specification.
- For std::thread::id and `std::stacktrace_entry`, see thread id format specification and stacktrace entry format specification.
- For `std::basic_stacktrace`, no format specifier is allowed.

(since C++23)

- For `std::filesystem::path`, see path format specification.

(since C++26)

- For other formattable types, the format specification is determined by user-defined `formatter` specializations.

args | - | arguments to be formatted

### Return value

(none)

### Exceptions

- std::bad_alloc on allocation failure.
- Propagate any exception thrown by any formatter, e.g. std::format_error, without regard to the value of os.exceptions() and without turning on ios_base::badbit in the error state of os.
- May throw ios_base::failure caused by os.setstate(ios_base::badbit) which is called if an insertion into os fails.

### Notes

Feature-test macro | Value | Std | Feature
--- | --- | --- | ---
`__cpp_lib_print` | `202207L` | (C++23) | Formatted output
`__cpp_lib_format` | `202207L` | (C++23) | Exposing std::basic_format_string

### Example

| This section is incomplete Reason: no example

### See also

vprint_unicode(std::ostream) (C++23) | performs Unicode aware output using type-erased argument representation (function)
print(std::ostream) (C++23) | outputs formatted representation of the arguments (function template)
operator<<(std::basic_ostream) | inserts character data or insert into rvalue stream (function template)
vprint_nonunicodevprint_nonunicode_buffered (C++23) | prints to stdout or a file stream using type-erased argument representation (function)
format (C++20) | stores formatted representation of the arguments in a new string (function template)

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