1.3 ISO C90

The compiler compiles ISO C90 C and also supports ARM extensions to ISO C90.

The compiler compiles C as defined by the 1990 C standard and addenda:

  • ISO/IEC 9899:1990. The 1990 International Standard for C.

  • ISO/IEC 9899 AM1. The 1995 Normative Addendum 1, adding international character support through wchar.h and wtype.h.

The compiler also supports several extensions to ISO C90.

Throughout this document, the term:


Means ISO C90, together with the ARM extensions.

Use the compiler option --c90 to compile C90 code. This is the default.

Strict C90

Means C as defined by the 1990 C standard and addenda.

Use the compiler options --C90 --strict to enforce strict C90 code. Since C90 is the default, you could omit --C90.

Standard C

Means C90 or C99 as appropriate.


Means any of C90, strict C90, C99, strict C99, and Standard C.

Related reference
8.23 --c90
8.173 --strict, --no_strict
1.6 Language extensions
1.7 Language compliance
15.1 Implementation definition
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