7.2 Run-Time Library Support of Type long double

Of the math packages offered by the Microsoft C/C++ compiler, only the emulator package and the math coprocessor package support the long double type; the alternate math package does not support it. In the math packages that support long double, each of the normal floating-point math functions has a special version that supports type long double. These functions have the same name as the functions that support type float and type double, except that they end with l. For example, the function that returns the absolute value of a variable of type float or type double is fabs. The long double equivalent function is _fabsl. The two exceptions to this rule are the _atold and _strtold functions.