json/api/macros/json_no_io.md

JSON_NO_IO

#define JSON_NO_IO

When defined, headers <cstdio>, <ios>, <iosfwd>, <istream>, and <ostream> are not included and parse functions relying on these headers are excluded. This is relevant for environments where these I/O functions are disallowed for security reasons (e.g., Intel Software Guard Extensions (SGX)).

Default definition

By default, #!cpp JSON_NO_IO is not defined.

#undef JSON_NO_IO

Examples

??? example

The code below forces the library not to use the headers `<cstdio>`, `<ios>`, `<iosfwd>`, `<istream>`, and
`<ostream>`.

```cpp
#define JSON_NO_IO 1
#include <nlohmann/json.hpp>

...
```

See also

• operator<< - serialize to stream
• operator>> - deserialize from stream
• Serialization - pretty-printing, UTF-8 handling, and number output
• Parsing - overview of the parsing functions

Version history

• Added in version 3.10.0.