{"id":5754,"date":"2022-02-19T19:25:08","date_gmt":"2022-02-19T18:25:08","guid":{"rendered":"http:\/\/miro.borodziuk.eu\/?p=5754"},"modified":"2026-01-24T14:13:37","modified_gmt":"2026-01-24T13:13:37","slug":"input-function","status":"publish","type":"post","link":"http:\/\/miro.borodziuk.eu\/index.php\/2022\/02\/19\/input-function\/","title":{"rendered":"Input() function"},"content":{"rendered":"

1. The print()<\/code> function sends data to the console<\/strong>, while the input()<\/code> function gets data from the console<\/strong>.<\/p>\n

<\/p>\n

2. The input()<\/code> function comes with an optional parameter: the prompt string<\/strong>. It allows you to write a message before the user input, e.g.:<\/p>\n

name = input(\"Enter your name: \")\r\nprint(\"Hello, \" + name + \". Nice to meet you!\")<\/pre>\n
 <\/p>\n
3. When the input()<\/code> function is called, the program’s flow is stopped, the prompt symbol keeps blinking (it prompts the user to take action when the console is switched to input mode) until the user has entered an input and\/or pressed the Enter<\/i> key.<\/p>\n
 <\/p>\n
NOTE<\/span><\/em><\/p>\n
The input()<\/code> function can be used to prompt the user to end a program. Look at the code below:<\/p>\n
\n
\n
name = input(\"Enter your name: \")\r\nprint(\"Hello, \" + name + \". Nice to meet you!\")\r\n\r\n\r\nprint(\"\\nPress Enter to end the program.\")\r\ninput()\r\nprint(\"THE END.\")<\/pre>\n
 <\/p>\n
4. The result of the input()<\/code> function is a string. You can add strings to each other using the concatenation (+<\/code>) operator. Check out this code:<\/div>\n<\/div>\n<\/div>\n
\n
\n
num_1 = input(\"Enter the first number: \") # Enter 12\r\nnum_2 = input(\"Enter the second number: \") # Enter 21\r\n\r\nprint(num_1 + num_2) # the program returns 1221<\/pre>\n
 <\/p>\n
5. You can also multiply (*<\/code> \u2012 replication) strings, e.g.:<\/p>\n<\/div>\n<\/div>\n
\n
\n
my_input = input(\"Enter something: \") # Example input: hello\r\nprint(my_input * 3) # Expected output: hellohellohello<\/pre>\n<\/div>\n<\/div>\n
<\/div>\n
\n
Type casting<\/h1>\n
Python offers two simple functions to specify a type of data and solve this problem – here they are: <\/code><\/p>\n
int()<\/pre>\n
and<\/p>\n
float()<\/pre>\n
Their names are self-commenting:<\/p>\n
    \n
  • the int()<\/code> function takes one argument<\/strong> (e.g., a string: int(string)<\/code>) and tries to convert it into an integer; if it fails, the whole program will fail too (there is a workaround for this situation, but we’ll show you this a little later);<\/li>\n
  • the float()<\/code> function takes one argument (e.g., a string: float(string)<\/code>) and tries to convert it into a float (the rest is the same).<\/li>\n<\/ul>\n
    Type conversion: str()<\/h1>\n
    This type of conversion is not a one-way street. You can also convert a number into a string<\/strong>, which is way easier and safer \u2012 this kind of operation is always possible.<\/p>\n
    A function capable of doing that is called str()<\/code>:<\/p>\n
    \n
    \n
    \n
    str(number)<\/pre>\n
     <\/p>\n
    Exercise 1<\/em><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    \n
    What is the output of the following snippet?<\/p>\n
    \n
    \n
    x = int(input(\"Enter a number: \")) # The user enters 2\r\nprint(x * \"5\")<\/pre>\n<\/div>\n<\/div>\n
    55<\/code><\/p>\n
     <\/p>\n
    Exercise 2<\/em><\/p>\n
    What is the expected output of the following snippet?<\/p>\n
    \n
    \n
    x = input(\"Enter a number: \") # The user enters 2\r\nprint(type(x))<\/pre>\n<\/div>\n<\/div>\n
    <class 'str'><\/code><\/p>\n<\/div>\n
     <\/p>\n
    Ex. 3<\/p>\n
    What is the output of the following snippet of the user enters two lines containing 2<\/code> and 4<\/code> respectively ?<\/p>\n
        x = input()\r\n    y = int(input())\r\n    print(x * y)<\/pre>\n
    \n
    \n
    A. <\/span>2222<\/code><\/div>\n<\/div>\n<\/div>\n
    \n
    \n
    B. <\/span>The code is erroneous.<\/div>\n
    C. 2 * 4<\/code><\/div>\n<\/div>\n<\/div>\n
    \n
    \n
    \n
    \n
    D. 8<\/code><\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    \n
    \n
    \n
    Explanation:<\/em><\/p>\n
    The input()<\/code> function always returns a string. So x<\/code> is a string.<\/p>\n
    The int()<\/code> function converts its argument (string, float, etc…) to an int. So, y<\/code> is an int.<\/p>\n
    The *<\/code> operator can be used with one string ABC and an int x : the result will be the string ABC repeated x times.<\/p>\n
    Try it yourself:<\/em><\/p>\n
        x = input(\"Enter x:\")        # enter 2\r\n    print(type(x))               # <class 'str'>\r\n     \r\n    y = int(input(\"Enter y:\"))   # enter 4\r\n    print(type(y))               # <class 'int'>\r\n     \r\n    print(x * y)                 # 2222<\/pre>\n<\/div>\n<\/div>\n<\/div>\n
     <\/p>\n
    Ex. 4<\/p>\n
    What is the expected output of the following code if :<\/p>\n
    (1) the user enters 10\/2<\/code> when prompted ?<\/p>\n
    (2) the user enters 3.1<\/code> when prompted ?<\/p>\n
        x = input(\"Enter number : \")\r\n    print(int(x))<\/pre>\n
    \n
    \n
    \n
    <\/div>\n<\/div>\n<\/div>\n<\/div>\n
    \n
    \n
    \n
    \n
    (1) : 5
    \n(2) : 3<\/p>\n
    (1) : 5
    \n(2) : The code will raise an unhandled exception<\/p>\n
    (1) : The code will raise an unhandled exception
    \n(2) : 3<\/p>\n
    (1) : The code will raise an unhandled exception
    \n(2) : The code will raise an unhandled exception<\/p>\n
     <\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n
    \n
    \n
    \n
    Explanation:<\/em><\/p>\n
    The input()<\/code> function returns a string.<\/p>\n
    The\u00a0 int()<\/code> function returns an integer object from any number or string – if the function cannot convert the object to an integer, an exception is raised.<\/p>\n
    Here in the above question, when the user enters 10\/2<\/code>, this will be treated as a string and the int()<\/code> function will not be able to convert this string into an integer –> an exception will be raised.<\/p>\n
    When the user enters 3.1<\/code> , this is also a string : the int()<\/code> function will not be able to convert this string into an integer –> an exception will be raised. If this had been a float, then int(3.1)<\/code> would have returned 3<\/code>.<\/p>\n
    Try it yourself:<\/em><\/p>\n
        x = input(\"Enter number : \") # enter 10\/2\r\n    print(int(x))    # exception\r\n     \r\n    x = input(\"Enter number : \") # enter 3.1\r\n    print(int(x))    # exception\r\n     \r\n    # Below, we convert the string to a float before calling int():\r\n    x = float(input(\"Enter number : \")) # enter 3.1\r\n    print(int(x))    # 3<\/pre>\n
     <\/p>\n<\/div>\n<\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"
    1. The print() function sends data to the console, while the input() function gets data from the console.<\/p>\n","protected":false},"author":2,"featured_media":5934,"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\/5754"}],"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=5754"}],"version-history":[{"count":10,"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/posts\/5754\/revisions"}],"predecessor-version":[{"id":6292,"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/posts\/5754\/revisions\/6292"}],"wp:featuredmedia":[{"embeddable":true,"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/media\/5934"}],"wp:attachment":[{"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/media?parent=5754"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/categories?post=5754"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/miro.borodziuk.eu\/index.php\/wp-json\/wp\/v2\/tags?post=5754"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}