parsing - Why would R use the "L" suffix to denote an integer? -

parsing - Why would R use the "L" suffix to denote an integer? -

in r know convenient times want ensure dealing integer specify using "l" suffix this:

1l # [1] 1

if don't explicitly tell r want integer assume meant utilize numeric info type...

str( 1 * 1 ) # num 1 str( 1l * 1l ) # int 1

why "l" preferred suffix, why not "i" instance? there historical reason?

in addition, why r allow me (with warnings):

str(1.0l) # int 1 # warning message: # integer literal 1.0l contains unnecessary decimal point

but not..

str(1.1l) # num 1.1 #warning message: #integer literal 1.1l contains decimal; using numeric value

i'd expect both either homecoming error.

why "l" used suffix?

i've never seen written down, theorise in short 2 reasons:

beacuse r handles complex numbers may specified using suffix "i" , simillar "i"

because r's integers 32-bit long integers , "l" hence appears sensible shorthand referring info type.

the value long integer can take depends on word size. r not natively back upwards integers word length of 64-bits. integers in r have word length of 32 bits , signed , hence have range of −2,147,483,648 2,147,483,647. larger values stored double.

this wiki page has more info on mutual info types, thier conventional names , ranges.

and ?integer

note current implementations of r utilize 32-bit integers integer vectors, range of representable integers restricted +/-2*10^9: doubles can hold much larger integers exactly.

why 1.0l , 1.1l homecoming different types?

the reason 1.0l , 1.1l homecoming different info types because returning integer 1.1 result in loss of information, whilst 1.0 not (but might want know no longer have floating point numeric). buried deep lexical analyser (/src/main/gram.c:4463-4485) code (part of function numericvalue()) creates int info type double input suffixed ascii "l":

class="lang-c prettyprint-override">/* create things okay. */ if(c == 'l') { double = r_atof(yytext); int b = (int) a; /* asked create integer via l, check double , int values same. if not, problem , not lose info , utilize numeric value. */ if(a != (double) b) { if(generatecode) { if(seendot == 1 && seenexp == 0) warning(_("integer literal %s contains decimal; using numeric value"), yytext); else { /* hide l warning message */ *(yyp-2) = '\0'; warning(_("non-integer value %s qualified l; using numeric value"), yytext); *(yyp-2) = (char)c; } } asnumeric = 1; seenexp = 1; } }

r parsing integer semantics