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In general, universal character names should be avoided in identifiers unless absolutely necessary. The basic character set should suffice for almost every identifier.

Noncompliant Code Example

This code example is noncompliant because it produces a universal character name by token concatenation.

#define assign(uc1, uc2, uc3, uc4, val) \
  uc1##uc2##uc3##uc4 = val;

int \U00010401\U00010401\U00010401\U00010402;
assign(\U00010401, \U00010401, \U00010401, \U00010402, 4);

Compliant Solution

This code solution is compliant.

#define assign(ucn, val) ucn = val;

int \U00010401\U00010401\U00010401\U00010402;
assign(\U00010401\U00010401\U00010401\U00010402, 4);

Risk Assessment

Creating a universal character name through token concatenation results in undefined behavior.

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website.

References

\[[ISO/IEC 10646-2003|AA. C References#ISO/IEC 10646-2003]\]
\[[ISO/IEC 9899:1999|AA. C References#ISO/IEC 9899-1999]\] Section 5.1.1.2, "Translation phases," Section 6.4.3, "Universal character names," and Section 6.10.3.3, "The ## operator"

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