How do I write a short literal in C++?

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Very basic question: how do I write a short literal in C++?

I know the following:

  • 2 is an int
  • 2U is an unsigned int
  • 2L is a long
  • 2LL is a long long
  • 2.0f is a float
  • 2.0 is a double
  • '\2' is a char.

But how would I write a short literal? I tried 2S but that gives a compiler warning.

literals c++
7 Answers
((short)2)

Yeah, it's not strictly a short literal, more of a casted-int, but the behaviour is the same and I think there isn't a direct way of doing it.

That's what I've been doing because I couldn't find anything about it. I would guess that the compiler would be smart enough to compile this as if it's a short literal (i.e. it wouldn't actually allocate an int and then cast it every time).

The following illustrates how much you should worry about this:

a = 2L;
b = 2.0;
c = (short)2;
d = '\2';

Compile -> disassemble ->

movl    $2, _a
movl    $2, _b
movl    $2, _c
movl    $2, _d
Admin1

Even the writers of the C99 standard got caught out by this. This is a snippet from Danny Smith's public domain stdint.h implementation:

/* 7.18.4.1  Macros for minimum-width integer constants

    Accoding to Douglas Gwyn <gwyn@arl.mil>:
    "This spec was changed in ISO/IEC 9899:1999 TC1; in ISO/IEC
    9899:1999 as initially published, the expansion was required
    to be an integer constant of precisely matching type, which
    is impossible to accomplish for the shorter types on most
    platforms, because C99 provides no standard way to designate
    an integer constant with width less than that of type int.
    TC1 changed this to require just an integer constant
    *expression* with *promoted* type."
*/
Mike_B_127110

One possibility is to use C++11 "list initialization" for this purpose, e.g.:

short{42};

The advantage of this solution (compared to a cast as in the currently accepted answer) is that it does not allow narrowing conversions:

auto number1 = short(100000); // Oops: Stores -31072, you may get a warning
auto number2 = short{100000}; // Compiler error. Value too large for type short

See https://en.cppreference.com/w/cpp/language/list_initialization#Narrowing_conversions for prohibited narrowing conversions with list-init

user_85106450

As far as I know, you don't, there's no such suffix. Most compilers will warn if an integer literal is too large to fit in whatever variable you're trying to store it in, though.

unwind_281690
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