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Nonetheless, it is recommended that string literals that are concatenated should all be the same type so as not to rely on implementation-defined behavior or undefined behavior if compiled on a platform that supports only C90.

Noncompliant Code Example (C90)

This noncompliant code example concatenates wide and narrow string literals. Although the behavior is undefined in this caseC90, the programmer probably intended to create a wide-string literal.

wchar_t *msg = L"This message is very long, so I want to divide it "
                "into two parts.";

Compliant Solution (C90, Wide String Literals)

If the concatenated string needs to be a wide string literal, each element in the concatenation must be a wide string literal, as in this compliant solution.

wchar_t *msg = L"This message is very long, so I want to divide it "
               L"into two parts.";

Compliant Solution (C90, Narrow String Literals)

If wide string literals are unnecessary, it is better to use narrow string literals, as in this compliant solution.

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