HP C/aC++ for PA-RISC Software manual Migration Considerations Related to Standardization

Obsolete Preprocessor Options

HP aC++ provides support for ANSI/ISO C++ International Standard preprocessing. Since the standard categorizes support of pre-ISO preprocessing as an anachronism, the ANSI preprocessing options of HP C++ (cfront) are not supported. For a list of obsolete preprocessor options, see Table 13: “Obsolete Command-Line Options” (page 200).

Migration Considerations Related to Standardization

The ANSI/ISO C++ International Standard redefines the rules, syntax, and features of C++ language. If your existing code contains any of the standards based keywords as variable names, you must change the variable names when you convert your program to an HP aC++ program. In addition to keyword changes, there are changes in C++ Semantics and C++ Syntax.

Changes in C++ Semantics

Following lists the differences in code behavior when you migrate from HP C++ to HP aC++:

•Implicit Typing of Character String Literals

•Overload Resolution Ambiguity of Subscripting Operator

•Execution Order of Static Constructors in Shared Libraries

•More Frequent Inlining of Inline Code

NOTE: These differences can occur inspite of compiling your code without errors.

Implicit Typing of Character String Literals

HP C++ implicitly types character string literals as char *. HP aC++, in accordance with the ANSI/ISO C++ International Standard, types character string literals as const char *. This difference affects function overloading resolution.

Example:

In the following code, HP aC++ calls the first function a; cfront calls the second.

void a(const char *); void a(char *);

f() { a(“A_STRING”);

}

To prevent existing code from breaking, assign a string literal to a non-const pointer.

Example:

char *p = “B_STRING”;

NOTE: This feature may not be a part of the Standard in future revisions.

Also, you cannot convert const char * to char *in a conditional expression in this context.

Example:

char *p = f() ? “A” : “B”;

In such a scenario, you must change the code.

Example:

const char *p = f() ? “A” : “B”;

or

char *p = const_cast(f() ? “A” : “B”);

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