How Do I Choose the Right C Standard When Compiling with g ?

Choosing the C Standard in g Compilations

Compiling C code with g requires consideration of the C standard version to avoid potential errors. By default, g uses a specific standard version, but it can be overridden using command-line arguments.

Default Standard Version

The default standard version used by g can be determined by executing the command:

g++ -dM -E -x c++ /dev/null | grep -F __cplusplus

This command outputs a macro that defines the __cplusplus preprocessor macro, indicating the version of the C standard being used. For example:

#define __cplusplus 199711L  // Represents C++98

Overriding the Default Version

To override the default standard version, use the -std= argument followed by the desired version. For instance, to use C 17, the command would be:

g++ -std=c++17 example.cpp

Recommendation

Using the -std= argument is recommended for several reasons:

• Ensures compatibility with the intended version of C .
• Prevents unexpected errors due to using an outdated or unsupported standard.
• Facilitates collaboration across different systems and toolchains with varying default standards.

References

• [g Options](https://gcc.gnu.org/onlinedocs/gcc/C_002b_002b-Options.html)
• [g Standard Version Query](https://gcc.gnu.org/onlinedocs/gcc/cpp-options.html#cpp-options_002dM)

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