Helpful Built-in Functions in C++ that All Devs Should Know

Built-in functions in C++ are those functions that are part of the C++ standard libraries. These functions are designed to provide common and essential functionality that is often required in programming.

In this article, we will look at some of the most commonly used built-in functions in C++ so you can start using them in your code.

What we’ll cover:

The `sqrt()` Function

You use the sqrt() function to determine the square root of the value of type double. It is defined inside the <cmath> header file.

Syntax:

sqrt (n)

Parameter: This function takes only one parameter of type double which is a number we want to find the square root of.

Return Type: The square root of the value of type double.

Example Code

Let’s look at an example so you can see how this function works:

// C++ program to see the use of sqrt() function
#include <cmath>     
#include <iostream>  

using namespace std;  
int main()
{
    double x = 100;

    double answer;

    // Use the sqrt() function to calculate the square root of the number
    answer = sqrt(x);

    // Print the result 
    cout << answer << endl;

    return 0;
}

Output:

The `pow()` Function

You use the pow() function to find the value of the given number raised to some power. This function is also defined inside the <cmath> header file.

Syntax:

double pow(double x, double y);

Parameters:

x: The base number.
y: The exponential power.

Return Type: value of x raised to the power y.

Example Code:

Let’s look at an example to see how this works:

// C++ program to see the use of the pow() function
#include <cmath>
#include <iostream>
using namespace std;

int main()
{
 // Declare an integer variable 'base' 
    int base = 5;

// Declare an integer variable 'exponent' 
    int exponent = 3;

// pow(5, 3) means 5^3 which is 5*5*5 = 125
// Use the pow() function to calculate base raised to the power of exponent
    int answer = pow(base, exponent);

// output the result
    cout << answer << endl;
}

Output:

125

The `sort()` Function

The sort() function is part of STL’s <algorithm> header. It is a function template that you can use to sort the random access containers, such as vectors, arrays, and so on.

Syntax:

sort (arr , arr + n, comparator)

Parameters:

arr: The pointer or iterator to the first element of the array.
arr + n: The pointer to the imaginary element next to the last element of the array.
comparator: The unary predicate function that is used to sort the value in some specific order. The default value of this sorts the array in ascending order.

Return Value: This function does not return any value.

Example Code:

Let’s look at an example:

#include <iostream>     
#include <algorithm>    // Header file that includes the sort() function

using namespace std;    

int main()
{
    // Declare and initialize an integer array with unsorted elements
    int arr[] = { 13, 15, 12, 14, 11, 16, 18, 17 };

    // Calculate the number of elements in the array
    int n = sizeof(arr) / sizeof(arr[0]);

    // Use the built-in sort() function from the algorithm library
    sort(arr, arr + n);

    // Print the sorted array using a loop
    for (int i = 0; i < n; ++i)
        cout << arr[i] << " ";  

    return 0;
}

Output:

11 12 13 14 15 16 17 18

The `find()` Function

The find() function is also part of the STL <algorithm> library. You use this function to find a value in the given range. You can use it with both sorted and unsorted datasets as it implements a linear search algorithm.

Syntax:

find(startIterator, endIterator, key)

Parameters:

startIterator: Iterates to the beginning of the range.
endIterator: Iterates to the end of the range.
key: The value to be searched.

Return Value: If the element is found, then the iterator is set to the element. Otherwise, it iterates to the end.

Example Code:

Let’s look at an example to better understand how it works:

// C++ program to see the the use of the find() function

#include <algorithm>   // Required for the find() function
#include <iostream>    
#include <vector>      

using namespace std;   

int main()
{
    // Initialize a vector 
    vector<int> dataset{ 12, 28, 16, 7, 33, 43 };

    // Use the find() function to search for the value 7
    auto index = find(dataset.begin(), dataset.end(), 7);

    // Check if the element was found
    if (index != dataset.end()) {
        // If found, print the position (index) by subtracting the starting iterator
        cout << "The element is found at the "
             << index - dataset.begin() << "nd index";
    }
    else {
        // If not found
        cout << "Element not found";
   }
    return 0;
}

Output:

The element is found at the 3rd index

The `binary_search()` Function

The binary_search() function is also used to find an element in the range – but this function implements binary search instead of linear search as compared to the find() function. It’s also faster than the find() function, but you can only use it on sorted datasets with random access. It’s defined inside the <algorithm> header file.

Syntax:

binary_search (starting_pointer , ending_pointer , target);

Parameters:

starting_pointer: Pointer to the start of the range.
ending_pointer: Pointer to the element after the end of the range.
target: Value to be searched in the dataset.

Return Value:

Returns true if the target is found.
Else return false.

Example Code:

Let’s check out an example to see how it works:

// C++ program for the binary_search() function

#include <algorithm>   
#include <iostream>    
#include <vector>      

using namespace std;   

int main()
{
    // Initialize a sorted vector of integers
    vector<int> arr = { 56, 57, 58, 59, 60, 61, 62 };

    // binary_search() works only on sorted containers
    if (binary_search(arr.begin(), arr.end(), 62)) {
        // If found, print that the element is present
        cout << 62 << " is present in the vector.";
    }
    else {
        // If not found, print that the element is not present
        cout << 16 << " is not present in the vector";
    }

    cout << endl;
}

Output:

62 is present in the vector.

The `max()` Function

You can use the std::max() function to compare two numbers and find the bigger one between them. It’s also defined inside the <algorithm> header file.

Syntax:

max (a , b)

Parameters:

a: First number
b: Second number

Return Value:

This function returns the larger number between the two numbers a and b.
If the two numbers are equal, it returns the first number.

Example Code:

Here’s an example:

// max() function

#include <algorithm>  
#include <iostream>   
using namespace std;

int main()
{
    // Declare two integer variables
    int a = 8 ;
    int b = 10 ;

    // Use the max() function to find the larger number between a and b
    int maximum = max(a, b);

    // Display the result with a meaningful message
    cout << "The maximum of " << a << " and " << b << " is: " << maximum << endl;

    return 0;
}

Output:

The maximum of 8 and 10 is: 10

The `min()` Function

You can use the std::min() function to compare two numbers and find the smaller of the two. It’s also defined inside the <algorithm> header file.

Syntax:

min (a , b)

Parameters:

a: First number
b: Second number

Return Value:

This function returns the smaller number between the two numbers a and b.
If the two numbers are equal, it returns the first number.

Example Code:

Here’s an example:

// use of the min() function

#include <algorithm>  // For the built-in min() function
#include <iostream>   
using namespace std;

int main()
{
    // Declare two integer variables to store user input
    int a = 4 ;
    int b = 8 ;

    // Use the min() function to find the smaller 
    int smallest = min(a, b);

    // Display the result 
    cout << "The smaller number between " << a << " and " << b << " is: " << smallest << endl;

    return 0;
}

Output:

The smaller number between 4 and 8 is: 4

The `swap()` Function

The std::swap() function lets you swap two values. It’s defined inside <algorithm> header file.

Syntax:

swap(a , b);

Parameters:

a: First number
b: Second number

Return Value: This function does not return any value.

Example:

Here’s how it works:

//  use of the swap() function

#include <algorithm>  // For the built-in swap() function
#include <iostream>   
using namespace std;

int main()
{
    int firstNumber = 8 ;
    int secondNumber = 9 ;


    // Use the built-in swap() function to exchange values
    swap(firstNumber, secondNumber);

    // Display values after swapping
    cout << "After the swap:" << endl;
    cout << firstNumber << " " << secondNumber << endl;

    return 0;
}

Output:

After the swap:

9 8

The `tolower()` Function

You can use the tolower() function to convert a given alphabet character to lowercase. It’s defined inside the <cctype> header.

Syntax:

tolower (c);

Parameter(s):

c: The character to be converted.

Return Value:

Lowercase of the character c.
Returns c if c is not a letter.

Example Code:

Here’s how it works:

// C++ program

// use of tolower() function

#include <cctype>     
#include <iostream>   
using namespace std;

int main()
{
    // Declare and initialize a string with uppercase characters
    string str = "FRECODECAMP";

    for (auto& a : str) {
        a = tolower(a);
    }

    // Print the modified string 
    cout << str;

    return 0;
}

Output:

freecodecamp

The `toupper()` Function

You can use the toupper() function to convert the given alphabet character to uppercase. It’s defined inside the <cctype> header.

Syntax:

toupper (c);

Parameters:

c: The character to be converted.

Return Value

Uppercase of the character c.
Returns c if c is not a letter.

Example Code:

Here’s how it works:

// use of toupper() function

#include <cctype>     
#include <iostream>   
using namespace std;

int main()
{
    // Declare and initialize a string 
    string str = "freecodecamp";

    for (auto& a : str) {
        a = toupper(a);
    }

    // Output the converted uppercase string
    cout << str;

    return 0;
}

Output:

FREECODECAMP

Conclusion

Inbuilt functions are helpful tools in competitive programming and in common programming tasks. These help in improving code readability and enhance the efficiency of code. In the above article, we discussed some very useful common inbuilt functions. Some common inbuilt functions are max(), min(), sort(), and sqrt(), etc. By using these inbuilt libraries, we can reduce boilerplate code and speed up the process of software development. These help in writing more concise, reliable, and maintainable C++ programs.

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How to Find the Area of a Square using Python?

How to Calculate the Area of a Circle using C++?

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Helpful Built-in Functions in C++ that All Devs Should Know

What we’ll cover:

The sqrt() Function

Syntax:

Example Code

The pow() Function

Syntax:

Example Code:

The sort() Function

Syntax:

Example Code:

The find() Function

Syntax:

Example Code:

The binary_search() Function

Syntax:

Example Code:

The max() Function

Syntax:

Example Code:

The min() Function

Syntax:

Example Code:

The swap() Function

Syntax:

Example:

The tolower() Function

Syntax:

Example Code:

The toupper() Function

Syntax:

Example Code:

Conclusion

Related Posts

The `sqrt()` Function

The `pow()` Function

The `sort()` Function

The `find()` Function

The `binary_search()` Function

The `max()` Function

The `min()` Function

The `swap()` Function

The `tolower()` Function

The `toupper()` Function