What does the "L" mean at the end of an integer literal?

Question

I have this constant:

#define MAX_DATE  2958465L

What does the L mean in this sense?

Slushy

It's not a constant but a macro (that expands to a literal). – Directorial

so what does the number expand to then? – Slushy

Answer 1

It is a long integer literal.

Integer literals have a type of int by default; the L suffix gives it a type of long (Note that if the value cannot be represented by an int, then the literal will have a type of long even without the suffix).

Galimatias

Sure? AFAIK literals without the 'L' suffix are of integer type in C++, and it will fail to compile if the literal will not fit in the int type. – Engagement

@David: "If it is decimal and has no suffix, it has the first of these types in which its value can be represented: int, long int (C++03 §2.13.1/2). – Galimatias

So it seems like compiler can choose for us automatically. When do we want to put in the L suffix ourselves? – Volscian

@kizzx2: 42 is an int. If you want it to be a long, you need to add the L (giving 42L). There are many reasons that you might want a long explicitly: you might do it to select a particular function overload or to ensure a template is instantiated with long instead of int. You might use it to ensure some integer expression is evaluated with long precision instead of int precision. INT_MAX + 1 will overflow. If long has greater range than int, INT_MAX + 1L will not overflow. – Galimatias

Answer 2

In this scenario the Ldoes nothing.

The L after a number gives the constant the long type, but because in this scenario the constant is immediately assigned to an int variable nothing is changed.

Figment

Could you give an example where it does do something? – Thallium

@Thallium This is useful: #13135456 – Covariance

Answer 3

L tells the compiler that the number is of type Long. Long is a signed type greater than or equal to an int in size. On most modern compilers, this means that the number will take 4 bytes of memory. This happens to be the same as an int on most compilers so it won't have an effect in this case.

Benedictbenedicta

long is signed, on mac os, using gcc, long is 8 byte long. – Hawkins

Answer 4

see this link it says :

Literal constants (often referred to as literals or constants) are invariants whose values are implied by their representations.

base:decimal

example:1L

description: Any decimal number (digits 0-9) not beginning with a 0 (zero) and followed by L or l

Alpheus