AUTOSAR C++14 Rule A13-1-2

Rule Definition

User defined suffixes of the user defined literal operators shall start with underscore followed by one or more letters.

Rationale

Since C++11, you can add suffixes to literals that convert numeric values under the hood. For instance, in code where you perform all calculations in a common unit, you can leave unit conversions to dedicated operators and simply use literal suffixes for the units when defining constant values.

In this example, the literal suffixes _m and _km resolve to calls to operator"" _m() and operator"" _km() respectively. The operators ensure that all values are converted to the same unit.

constexpr long double operator"" _m(long double metres) {
    return metres;
}

constexpr long double operator"" _km(long double kilometres) {
    return 1000*kilometres;
}
...
long double minSteps = 100.0_m;
long double interCityDist = 100.0_km;

User defined literal suffixes must begin with an underscore (_). Literal suffixes not beginning with underscore are reserved for the Standard Library.

Polyspace Implementation

The rule checker flags definitions of the form:

operator "" suffix

Troubleshooting

If you expect a rule violation but Polyspace^® does not report it, see Diagnose Why Coding Standard Violations Do Not Appear as Expected.