What's the Difference Between Long Long and Long

What's the difference between long long and long

Going by the standard, all that's guaranteed is:

• int must be at least 16 bits
• long must be at least 32 bits
• long long must be at least 64 bits

On major 32-bit platforms:

• int is 32 bits
• long is 32 bits as well
• long long is 64 bits

On major 64-bit platforms:

• int is 32 bits
• long is either 32 or 64 bits
• long long is 64 bits as well

If you need a specific integer size for a particular application, rather than trusting the compiler to pick the size you want, #include <stdint.h> (or <cstdint>) so you can use these types:

• int8_t and uint8_t
• int16_t and uint16_t
• int32_t and uint32_t
• int64_t and uint64_t

You may also be interested in #include <stddef.h> (or <cstddef>):

• size_t
• ptrdiff_t

What is the difference between long , long long , long int , and long long int in C++?

long and long int are identical. So are long long and long long int. In both cases, the int is optional.

As to the difference between the two sets, the C++ standard mandates minimum ranges for each, and that long long is at least as wide as long.

The controlling parts of the standard (C++11, but this has been around for a long time) are, for one, 3.9.1 Fundamental types, section 2 (a later section gives similar rules for the unsigned integral types):

There are five standard signed integer types : signed char, short int, int, long int, and long long int. In this list, each type provides at least as much storage as those preceding it in the list.

There's also a table 9 in 7.1.6.2 Simple type specifiers, which shows the "mappings" of the specifiers to actual types (showing that the int is optional), a section of which is shown below:

Specifier(s)         Type
-------------    -------------
long long int    long long int
long long        long long int
long int         long int
long             long int

Note the distinction there between the specifier and the type. The specifier is how you tell the compiler what the type is but you can use different specifiers to end up at the same type.

Hence long on its own is neither a type nor a modifier as your question posits, it's simply a specifier for the long int type. Ditto for long long being a specifier for the long long int type.

Although the C++ standard itself doesn't specify the minimum ranges of integral types, it does cite C99, in 1.2 Normative references, as applying. Hence the minimal ranges as set out in C99 5.2.4.2.1 Sizes of integer types <limits.h> are applicable.

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In terms of long double, that's actually a floating point value rather than an integer. Similarly to the integral types, it's required to have at least as much precision as a double and to provide a superset of values over that type (meaning at least those values, not necessarily more values).

When to use Long vs long in java?

I don't think there's a single correct answer. A few suggestions:

• The biggest difference I see between long and Long in this context is that Long may be null. If there's a possibility you might have missing values, the Long object will be helpful as null can indicate missing values. If you're using primitives, you'll have to use some special value to indicate missing, which is probably going to be a mess. Speed or size is not likely to be an issue unless you're planning on making an array of a million of these things and then serializing.

• My preference for validation logic is to throw some sort of custom ValidationException at the point at which the thing could fail. If you're just creating these things with a constructor, the simplest thing would be just to validate there, e.g.

   public ClientInput(Long userid, Long clientid, Map<String, String> parameterMap, Long timeout_ms, boolean debug) throws ValidationException {          
  
        if (userid == null) throw new ValidationException("UserId is required"); 
              ...etc, etc...
  }
  

Ultimately, the ValidationException is only useful if you can catch it at a point where you can do something useful with it - echo it back to a user or whatever.

What is the difference between long long and long int

There are several shorthands for built-in types.

• short is (signed) short int
• long is (signed) long int
• long long is (signed) long long int.

On many systems, short is 16-bit, long is 32-bit and long long is 64-bit. However, keep in mind that the standard only requires

sizeof(char) == 1
sizeof(char) <= sizeof(short) <= sizeof(int) <= sizeof(long) <= sizeof(long long)

And a consequence of this is that on an exotic system, sizeof(long long) == 1 is possible.

Difference between long and long long

C types are intended to be flexible, so they can be adapted to different situations in different C implementations. Because of this, in some C implementations, long and long long are the same width (number of bits used for the value) and size (total number of bytes, including padding). (Some other types can be the same size. For example, short and int can be the same.)

In a C implementation where long and long long are the same width and size, there is no arithmetic difference between them. There are technical differences. In particular, a pointer to a long is a different type from a pointer to a long long, and you should not use one where the other is expected.

Difference between Short, long and Long long int in C programming?

C was originally written for 16-bit machines, where the fastest and most-convenient size of integer to work with were 16 bits. This was the original int type. Sometimes, programmers needed 32-bit numbers, so those were the long int type.

In due course, people ported C to 32-bit machines where the most convenient word size was 32 bits. They wanted to keep using int to mean the native word size, because for example about every C program in the real world has int i; in it somewhere, but sometimes, they also needed to use 16-bit numbers to save space. So those became the short int type.

Time passed, and C needed to be ported to 64-bit machines. By then, there were a lot of programs in existence that assumed long was exactly 32 bits wide, and unfortunately, a lot of programs that also assumed that a long was the same size as a pointer, an IPv4 address, a file offset, a timestamp, etc. Good code uses types such as size_t, uintptr_t, and off_t instead, but old versions of the system libraries defined their library functions to use long, so a lot of legacy code had to as well. Since C99 came out, there have also been types such as int32_t in the standard library to specify exact widths, and Unix and Windows have had them under different names for a while.

As a consequence of the types being used to mean contradictory things, compilers today give programmers the choice between long being 32 and 64 bits wide, and 64-bit compilers let int be either 32 or 64 bits wide, too. At least one real compiler defined int as 64 bits (the native word length) but long as 32 bits (so the system libraries and code would still work). The standards committee prohibited that in C11: long long int is now guaranteed to be at least as wide as long int, and long int at least as wide as int.

Because a lot of programs couldn't redefine long as 64 bits without breaking, C needed a new type that meant (at least) 64-bit. By then, the standards committee was reluctant to introduce new keywords outside a header file, so they reused an existing one instead and named it long long int.

In brief, you shouldn’t make assumptions about what int and long mean beyond that int is at least 16 bits wide and fast, long is at least 32 bits wide, and on a C11 compiler long is at least as wide as int but no wider than long long. For general purposes, use int. If you need an array index, use size_t or ptrdiff_t. If you want to be sure you can hold a number over 32,767, and seriously expect you might need to run on some 16-bit machine someday, use long or the fast type from <inttypes.h>. If you’re making a system call, use the same type as its arguments. If you’re storing a pointer in an integer type, use uintptr_t. If you need a number at least 64 bits wide, use long long, and if you know exactly the width you need, use the exact-width type.

Long Double vs Long Long

long long is integer (possibly with more range than long)

long double is floating point (possibly with more range/precision than double)

long float does not exist.

The integer types sorted by range are

• _Bool
• char or signed char or unsigned char
• short (or short int) or short unsigned
• int or unsigned
• long (or long int) or long unsigned
• long long (or long long int) or long long unsigned

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The floating-point types sorted by range/precision are

• float
• double
• long double

What is the difference between long and Long in android code?

Long is a class. long is a primitive. That means Long can be null, where long can't. Long can go anywhere that takes an Object, long can't (since it isn't a class it doesn't derive from Object).

Java will usually translate a Long into a long automatically (and vice versa), but won't for nulls (since a long can't be a null), and you need to use the Long version when you need to pass a class (such as in a generic declaration).

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