String Processing with Perl - On The Case (
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The next few string functions come in very handy when adjusting the case of a text string from lower- to upper-case, or vice-versa:
lc() - convert string to lower case
uc() - convert string to upper case
ucfirst() - convert the first character of string to upper case
lcfirst() - convert the first character of a string to lower case
Here's an example:
#!/usr/bin/perl
$str = "Something's rotten in the state of Denmark";
# returns "something's rotten in the state of denmark"
print lc($str);
# returns "SOMETHING'S ROTTEN IN THE STATE OF DENMARK"
print uc($str);
# returns "something's rotten in the state of Denmark"
print lcfirst($str);
# re-initialize for next bit of code
$str = "something's rotten in the state of Denmark";
# returns "Something's rotten in the state of Denmark"
print ucfirst($str);
You've already used the print() function extensively to display output. However, the print() function doesn't allow you to format output in any significant manner - for example, you can't write 1000 as 1,000 or 1 as 00001. And so clever Perl developers came up with the sprintf() function, which allows you to define the format in which data is printed.
Consider the following example:
#!/usr/bin/perl
# returns 1.6666666666667
print(5/3);
As you might imagine, that's not very friendly. Ideally, you'd like to display just the "significant digits" of the result. And so, you'd use the sprintf() function:
#!/usr/bin/perl
# returns 1.67
print sprintf("%1.2f", (5/3));
A quick word of explanation here: the Perl's sprintf() function is very similar to the printf() function that C programmers are used to. In order to format the output, you need to use "field templates", templates which represent the format you'd like to display.
Some common field templates are:
%s - string
%d - decimal number
%x - hexadecimal number
%o - octal number
%f - float number
You can also combine these field templates with numbers which indicate the number of digits to display - for example, %1.2f implies that Perl should only display two digits after the decimal point. If you'd like the formatted string to have a minimum length, you can tell Perl which character to use for padding by prefixing it with a single quote (').
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