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This article mainly introduces how to achieve automatic conversion between Perl numbers and strings, the article is very detailed, has a certain reference value, interested friends must read it!

Automatic conversion between Perl numbers and strings

Perl automatically converts between numbers and strings as needed:

1. Automatic conversion is based on operators. If the operator requires a number, it converts the string to a number; if a string is needed, all the numbers are converted to a string.

"12". "3" equals "123"

"12" * "3" equals 36

"z" .5 * 3 "is equivalent to" z ".15 is equivalent to" Z15 "

2. There is no doubt about the conversion of numbers to strings.

3. String to number:

When converting, find the string * numeric parts, and then remove the following non-numeric parts and the previous ones, for example, "12adsfasdlkf34234fsd234" * 3 equals 12 to 3 equals 36. If there is no number in the string, it is converted to 0.

For non-decimal numbers, the'0' prefix is valid only for numbers and is not useful for automatic conversion. For example, "0xab" * 0x12 does not treat the preceding "0xab" as a hexadecimal number.

4. Perl will remember the results of the conversion, so there is no need to worry about efficiency.

Here are some things to keep in mind about Perl strings:

1. In Perl, the shortest string is empty, and the longest string is full of memory.

2. Strings in Perl can include any character, which means you can create, traverse, and manipulate binary data.

3. In Perl, null has no special meaning.

4. Single quote string

Single quotation marks represent the beginning and end of a string

Only single quotes' and backslashes\ are special characters, and all other characters represent themselves, including newline characters. In other words, in a single quote string, you need to escape only if single quotation marks and backslashes are used. For example, if you write\ n in a string, it will not be treated as a newline character, but just two ordinary characters\ and n.

For\, only when it is followed by\ and 'will it be treated as a special character.

5. Double quotation mark string

It is the same as the strings we are familiar with in other languages. \ will be treated as escape characters.

It also has a unique feature: variable interpolation. That is, when a string contains a variable name, it replaces it with a variable value.

6. Join operator.

For example, "Hello". "World!" The result is "HelloWorld!"

The repeat operator x is a lowercase letter. To the left of the operator is a string, to the right of the operator is a number, and the result is the number of times the string is repeated. For example, "hello" x5, the operation result is "hellohellohellohellohello"

Note: when the number to the right of x is a non-integer, it will be converted to an integer less than or equal to it, for example, 4.8 will be converted to 4, and when this number is less than 1, an empty string will be generated.

The above is all the contents of the article "how to automatically convert Perl numbers and strings". Thank you for reading! Hope to share the content to help you, more related knowledge, welcome to follow the industry information channel!

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