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Python
docs.python.org › 3 › builtins › functions.html
Built-in Functions — Python 3.14.8 documentation
Syntax errors are reported as exceptions. ... This function executes arbitrary code. Calling it with untrusted user-supplied input will lead to security vulnerabilities. The source argument is parsed and evaluated as a Python expression (technically speaking, an expression list) using the globals and locals mappings as global and local namespace. If the globals dictionary is present and does not contain a value for the key __builtins__, a reference to the dictionary of the built-in module builtins is inserted under that key before source is parsed.
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Uchicago
ds1.datascience.uchicago.edu › 03 › 5 › 1 › BuiltIn.html
Built-In Functions and Methods — Introduction to Data Science
Built-in functions are, as the name implies, already a part of the Python library. These are functions that are so commonly used that you just need to call them in order to use them yourself! We have already seen a few examples of built-in functions including print() and type().
Discussions

As a beginner when to use built-in functions and when to write those myself?
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January 25, 2024
What are ALL of the basic functions in C (without libraries)
Actually, this is a GREAT question, because it approaches the philosophy of C. I don't like the fact that people are downvoting you. I don't understand why this sub is like this. Whatever, my answer is: None. Literally none. There are no functions at all without libraries. C, by itself, only provides syntax and language rules. But there is the standard library that is linked by default with lots of basic functions, like printf, scanf, malloc, etc. The standard library evolves with new versions of C. There is the C89/C90, the C99, the C11, the C17, and the C23. More on reddit.com
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September 29, 2024
What are some common PHP built-in functions you have to google even though you use them constantly?
Maybe you already knew this but With php 8.1 you can just use str_contains now it’s way simpler they literally did it to fix how annoying it was before as in your example. I find myself googling needle and haystack orders often for diff functions I don’t use often. More on reddit.com
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Attending my first matlab class . What are the things I should remember ?
Vectorization. A lot of for loops can be vectorized and matlab is optimized for it. More on reddit.com
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May 12, 2022
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IBM
ibm.com › docs › en › i › 7.4.0
Built-in Functions
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NinjaOne
ninjaone.com › home › it hub › built-in functions: definition & examples
Built-In Functions: Definition & Examples | NinjaOne
May 12, 2025 - Built-in functions refer to those pre-defined functions that come along with a programming language. They are intrinsic components of the language’s library, ready to be used without requiring any additional installation or importation.
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Reddit
reddit.com › r/learnprogramming › as a beginner when to use built-in functions and when to write those myself?
r/learnprogramming on Reddit: As a beginner when to use built-in functions and when to write those myself?
January 25, 2024 -

Hi!

I've been learning Python at school, but at home I've taken more and more interest in learning C++. I have no clue why, but cpp is just more stimulating.

At school we've been learning about different concepts (?) at a very basic introductory level in Python (enumerate, matrixes/2d arrays, dictionaries, functions), and I've been "translating" or trying to find an equivalent of those in cpp to get familiar with the syntax and how the language works.

So my question is it better for me as a beginner to use the built-in functions offered by languages in general, or should I write them myself. For example

How should I get the largest int from a list?

list = [112, 23, 3, 4, 54]
def biggest_int(input_list):
maximum = input_list[0]
for number in list:
    if number > maximum:
        maximum = number
return maximum

OR

print(max(list))

what I've done in cpp:

#include <vector>
std::vector<int> numbers = {1, 2, 4, 58, 68, 23, 45, 56};  
int maximum = numbers[0];

for (int number : numbers) { if (number > maximum) { maximum = number; } }

or

return *std::max_element(numbers.begin(), numbers.end());

I know these are not 1:1 translations or exactly the same methods/versions, but I think these demonstrate what I am trying to ask

Thanks in advance, and please tell me if the question isn't clear enough.

Top answer
1 of 7
7
Generally, you should be using standard library functions where available UNLESS you have a good reason not to. They are just tools in the box. Reasons might include: Performance (std::regex for example is notoriously slow compared to 3rd party options). Compatibility - you're stuck compiling for C++11 but you want to use feature X from C++20, you might have to implement it yourself. Platform limitations (some embedded devices for example have limited memory and dynamic allocations are avoided) The idea of the std library in C++ isn't to provide the best implementations of everything (partly because you can't really optimize everything, something has to suffer). The idea is to offer a hopefully useful toolset and to make it available on as many platforms as possible while being as generic as possible. If your needs aren't being met by one of the standard tools, it's time to investigate something more suitable. All that said, implementing functions yourself is a great way to understand how things are happening under the hood, which in turn makes you a better developer. Just save it for toy projects :)
2 of 7
3
It’s best not to reinvent the wheel. In the majority of cases, the standard library will almost always suffice. The only time you would probably want to deviate from that rule is if you’re trying to write something that’s extremely optimized and the trade-off between time expended on writing alternative code and the increase in optimization is worth it. I once tried to replace a function in Python’s itertools library and ended up spending a lot of time to get a minimal increase in performance. Of course, there are always exceptions to the rule; but when starting off with any language, I would use the standard library initially.
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Codefinity
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Learn Built-In Functions | What Is a Function in Python?
Built-in functions in Python are predefined and available for use without any additional setup. One example is the print() function, which you have already used.
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Medium
medium.com › @pies052022 › python-built-in-functions-with-examples-a3e13e0f9367
Python Built-in Functions with Examples | by JOKEN VILLANUEVA | Medium
October 14, 2025 - Built-in functions are part of the Python programming language itself and provide essential functionality for various operations.
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Quora
quora.com › What-is-a-built-in-function-in-C-1
What is a built-in function in C? - Quora
Answer: Built-in functions are those functions which are already pre-defined in the c standard library. This means that you can directly use the function in your program without worrying about how the function was built. The second type of functions are user -defined functions where you basically...
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Medium
medium.com › @fawazcp › python-built-in-functions-or-method-ba4255210e96
Python Built-in Functions or Method | by Fawaz C P | Medium
August 3, 2023 - The Python built-in functions are defined as the functions whose functionality is pre-defined in Python. The Python interpreter has several functions that are always present for use.
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Tutorialspoint
tutorialspoint.com › python › python_built_in_functions.htm
Python - Built-in Functions
Built-in functions are those functions that are pre-defined in the Python interpreter and you don't need to import any module to use them. These functions help to perform a wide variety of operations on strings, iterators, and numbers.
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Real Python
realpython.com › python-built-in-functions
Python Built-in Functions: A Complete Guide – Real Python
May 18, 2026 - Python’s built-in functions are predefined functions you can use anywhere in your code without any imports. They handle common tasks across math, data type creation, iterable processing, and input and output.
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GeeksforGeeks
geeksforgeeks.org › c++ › useful-inbuilt-functions-in-cpp
Useful Inbuilt Functions in C++ - GeeksforGeeks
October 16, 2023 - In-built functions in C++ are those functions that are part of C++ standard libraries. The purpose of inbuilt functions is to provide common and essential functionality that is frequently required in the programming.
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Python Morsels
pythonmorsels.com › built-in-functions-in-python
Built-in Functions in Python - Python Morsels
March 9, 2022 - Learn these later: these built-ins are generally useful to know about, but you'll find them when/if you need them · Maybe learn these eventually: these can come in handy, but only in specific circumstances · You likely don't need these: you're unlikely to need these unless you're doing something fairly specialized · The built-in functions in categories 1 and 2 are the essential built-ins that nearly all Python programmers should eventually learn about.
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Wolfram
wolfram.com › language › fast-introduction-for-programmers › en › built-in-functions
Built-in Functions | Wolfram Language Fast Introduction for Programmers
The built-in functions in the Wolfram Language are integrated into the language and follow a single uniform design, rather than being in different libraries.
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Webopedia
webopedia.com › home › definitions › built-in function
What is Built-In Function? | Webopedia
July 20, 2022 - A built-in function is a function that is already available in a programming language, application, or another tool that can be accessed by end users.
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W3Schools
w3schools.com › php › php_functions.asp
PHP Functions
PHP has over 1000 built-in functions that can be called directly, from within a script, to perform a specific task. Please check out our PHP reference for a complete overview.