A value directly written into the source code of a computer program (as opposed to an identifier like a variable or constant). Literals cannot be changed. Common types of literals include string literals, floating point literals, integer literals, and hexidemal literals. Literal strings are usually either quoted (") or use an apostrophe (') which is often referred to as a single quote. Sometimes quotes are inaccurately referred to as double quotes.
Languages Focus: Literals
In addition to understanding whether to use a quote or apostrophe for string literals, you also want to know how to specify and work with other types of literals including floating point literals. Some compilers allow leading and trailing decimals (.1 + .1), while some require a leading or trailing 0 as in (0.1 + 0.1). Also, because floating point literals are difficult for compilers to represent accurately, you need to understand how the compiler handles them and how to use rounding and trimming commands correctly for the nature of the project your are coding.
Perl Literals
String literals are quoted as in "Prestwood". If you need to embed a quote use a slash in front of the quote as in \".
To specify a floating point literal between 1 and -1, you can preceed the decimal with a 0 or not (both work). In other words, preceding and following decimals are allowed (both .1 and 0.1). Trailing decimals are also allowed (1, 1., and 1.0 are all equivalent and allowed).
Syntax Example: print "Hello";
print "Hello \"Mike\".";
#Does Perl evaluate this simple
#floating point math correctly? No!
if ((.1 + .1 + .1) == .3) {
print("Correct");
} else {
print("Not correct");
}
Working Example
#!/usr/local/bin/perl -w
print("Content-type: text/html\n\n");
#Start of HTML page.
print("<html>");
print("<head><title>Perl Literals</title></head>");
print("<body>");
if ((.1 + .1 + .1) == .3) {
print("Correct");
} else {
print("Not correct");
}
#Trailing decimals.
if ((1.0 + 1. + 1) == 3) {
print("Correct");
} else {
print("Not correct");
}
print("</body></html>");
Perl
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