{"id":5735,"date":"2022-01-15T10:23:44","date_gmt":"2022-01-15T09:23:44","guid":{"rendered":"http:\/\/miro.borodziuk.eu\/?p=5735"},"modified":"2024-06-17T19:01:27","modified_gmt":"2024-06-17T17:01:27","slug":"literals","status":"publish","type":"post","link":"http:\/\/miro.borodziuk.eu\/index.php\/2022\/01\/15\/literals\/","title":{"rendered":"Literals"},"content":{"rendered":"

1. Literals<\/strong> are notations for representing some fixed values in code. Python has various types of literals – for example, a literal can be a number (numeric literals, e.g., 123<\/code>), or a string (string literals, e.g., “I am a literal.”).<\/p>\n

<\/p>\n

2. The binary system<\/strong> is a system of numbers that employs 2<\/i> as the base. Therefore, a binary number is made up of 0s and 1s only, e.g., 1010<\/code> is 10<\/i> in decimal.<\/p>\n

Octal and hexadecimal numeration systems, similarly, employ 8<\/i> and 16<\/i> as their bases respectively. The hexadecimal system uses the decimal numbers and six extra letters.<\/p>\n

3. Integers<\/strong> (or simply int<\/strong>s) are one of the numerical types supported by Python. They are numbers written without a fractional component, e.g., 256<\/code>, or -1<\/code> (negative integers).<\/p>\n

4. Floating-point<\/strong> numbers (or simply float<\/strong>s) are another one of the numerical types supported by Python. They are numbers that contain (or are able to contain) a fractional component, e.g., 1.27<\/code>.<\/p>\n

5. To encode an apostrophe or a quote inside a string you can either use the escape character, e.g., 'I\\'m happy.'<\/code>, or open and close the string using an opposite set of symbols to the ones you wish to encode, e.g., \"I'm happy.\"<\/code> to encode an apostrophe, and 'He said \"Python\", not \"typhoon\"'<\/code> to encode a (double) quote.<\/p>\n

6. Boolean values<\/strong> are the two constant objects True<\/code> and False<\/code> used to represent truth values (in numeric contexts 1<\/code> is True<\/code>, while 0<\/code> is False<\/code>.<\/p>\n

 <\/p>\n

EXTRA<\/b><\/span><\/p>\n

There is one more, special literal that is used in Python: the None<\/code> literal. This literal is a so-called NoneType<\/code> object, and it is used to represent the absence of a value<\/strong>. We’ll tell you more about it soon.<\/p>\n

 <\/p>\n

Exercise 1<\/p>\n

What types of literals are the following two examples?<\/p>\n

\"Hello \", \"007\"<\/code><\/p>\n

They’re both strings\/string literals.<\/p>\n

 <\/p>\n

Exercise 2<\/p>\n

What types of literals are the following four examples?<\/p>\n

\"1.5\", 2.0, 528, False<\/code><\/p>\n

The first is a string, the second is a numerical literal (a float), the third is a numerical literal (an integer), and the fourth is a boolean literal.<\/p>\n

 <\/p>\n

Exercise 3<\/p>\n

What is the decimal value of the following binary number?<\/p>\n

1011<\/code><\/p>\n

It’s 11<\/code>, because (2**0) + (2**1) + (2**3) = 11<\/span><\/p>\n

 <\/p>\n

Ex. 4<\/p>\n

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Which of the following print<\/strong><\/code> statements displays the integer decimal 1000<\/strong><\/code> (one thousand<\/strong>) on the screen?<\/p>\n<\/div>\n<\/div>\n<\/div>\n

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print(1_0_0_0)<\/code><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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print(1,000)<\/code><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

\n
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print(01000)<\/code><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

\n
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print(1_000)<\/code><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

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<\/div>\n
<\/div>\n
<\/div>\n
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Correct selection<\/span><\/div>\n
\n
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print(1_0_0_0)<\/strong><\/code><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

\n
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print(1_000)<\/strong><\/code><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n

\n
print(1,000) # 1 0\r\nprint(1_0_0_0) # 1000\r\n# print(01000) # SyntaxError\r\nprint(1_000) # 1000<\/pre>\n<\/div>\n
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    \n
  • The print(1_0_0_0)<\/strong><\/code> and print(1_000)<\/strong><\/code> statements are correct<\/strong>.. Starting with version 3.6<\/strong>, Python allows the use of underscores<\/strong> in numeric literals to increase their readability when they are very large.<\/li>\n
  • print(1,000)<\/strong><\/code> is incorrect<\/strong>. It is equal to print(1, 0)<\/strong><\/code> and outputs 1 0<\/strong><\/code> on the screen.<\/li>\n
  • print(01000)<\/strong><\/code> is incorrect<\/strong> because in Python leading zeros<\/strong> in decimal integer<\/strong> literals<\/strong> are not allowed.<\/li>\n<\/ul>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
     <\/p>\n
    Ex. 5<\/p>\n
    What is the output of the following code snippet?<\/p>\n
    \n
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    n = 0\r\nfor i in \"\\'Monthy Python\\'\":\r\n  n += 1\r\n\r\nprint(n)<\/pre>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    \n
    \n
    \n
    <\/div>\n
    Correct answer<\/span><\/div>\n
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    15<\/strong><\/code><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    \n
    The loop counts the number of characters in the string str<\/strong><\/code>. The escape sequence \\'<\/strong><\/code>, representing the single<\/strong> quotation<\/strong> mark<\/strong>, is counted as a single character<\/strong>. Therefore, the total number of characters, including the space, is 15<\/strong><\/code>.<\/div>\n<\/div>\n<\/div>\n
    <\/div>\n
    <\/div>\n
    Ex. 6<\/div>\n
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    What is the output of the following code snippet?<\/p>\n
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    x = int(3.5)\r\ny = str(3)\r\nz = float(0)\r\n\r\nprint(x, y, z)<\/pre>\n
     <\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    \n
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    <\/div>\n<\/div>\n
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    Correct answer<\/span><\/div>\n
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    3 3 0.0<\/strong><\/code><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    \n
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    <\/div>\n<\/div>\n<\/div>\n<\/div>\n
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    • The int()<\/strong><\/code> function converts a number or string to an integer. If the number is a float, the function discards the decimal part.<\/li>\n
    • The str()<\/strong><\/code> function converts a value to a string.<\/li>\n
    • The float()<\/strong><\/code> function converts a number or string to a float, including 0<\/strong><\/code>.<\/li>\n
    • By default, the print()<\/strong><\/code> function does not print quotation marks of a string:\n
      print(x, y, z)<\/strong><\/code> -><\/strong> print(3, '3', 0.0)<\/strong><\/code> -><\/strong> 3 3 0.0<\/strong><\/code><\/li>\n<\/ul>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
      <\/div>\n","protected":false},"excerpt":{"rendered":"
      1. Literals are notations for representing some fixed values in code. Python has various types of literals – for example, a literal can be a number (numeric literals, e.g., 123), or a string (string literals, e.g., “I am a literal.”).<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[100],"tags":[],"_links":{"self":[{"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/posts\/5735"}],"collection":[{"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/comments?post=5735"}],"version-history":[{"count":9,"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/posts\/5735\/revisions"}],"predecessor-version":[{"id":5891,"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/posts\/5735\/revisions\/5891"}],"wp:attachment":[{"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/media?parent=5735"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/categories?post=5735"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/tags?post=5735"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}