Lära Positional and Default Arguments | Function Arguments Specification

Positional arguments

Positional arguments are a way of passing values to a function in a specific order based on the function's signature. The values are associated with parameters according to their positions in the parameter list of function signature. The position of each argument determines which parameter it corresponds to.

main.cpp


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#include <iostream>

// Function that takes two positional arguments
float divide(float a, float b)
{
    if (b == 0) 
        return 0;
    
    return a / b;
}

int main()
{
    float x = 8;
    float y = 4;

    // Calling the 'divide' function with two positional arguments
    float result = divide(x, y);
    std::cout << result << std::endl;
}

You can conduct a small experiment: change the order of passing arguments to the function (use divide (y, x) instead of divide(x, y)), and you will see that the result has changed. This is precisely the essence of positional arguments: the order of passing parameters to the function is important, directly affecting its result.

Default arguments

Default arguments let you assign default values to function parameters. If a function is called without providing all arguments, the missing ones use their default values. To set a default, just give the parameter a value directly in the function declaration.

main.cpp


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#include <iostream>

// Default value is set for the third parameter
float divide(float a, float b, bool terminate = true)
{
    if (b == 0) 
    {
        if (terminate)
            return 0;
        
        return a / 0.000001; // Prevent crash by using a very small number
    }

    return a / b;
}

int main()
{
    std::cout << divide(10, 2) << std::endl;        // Normal division
    std::cout << divide(10, 0) << std::endl;        // Default behavior (error)
    std::cout << divide(10, 0, false) << std::endl; // Forced division
}

The divide() function divides one number by another. If the denominator (b) is zero:

terminate = true → returns 0
terminate = false → divides by a tiny number to avoid an error

The terminate parameter has a default value of true, so it can be omitted. Set terminate = false to continue the calculation instead of stopping.

Note

It is important that all default arguments are located after the positional ones in the list of parameters. Otherwise, the compiler will throw an error.

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Positional arguments

main.cpp


              1234567891011121314151617181920
            
#include <iostream>

// Function that takes two positional arguments
float divide(float a, float b)
{
    if (b == 0) 
        return 0;
    
    return a / b;
}

int main()
{
    float x = 8;
    float y = 4;

    // Calling the 'divide' function with two positional arguments
    float result = divide(x, y);
    std::cout << result << std::endl;
}

Default arguments

main.cpp


              12345678910111213141516171819202122
            
#include <iostream>

// Default value is set for the third parameter
float divide(float a, float b, bool terminate = true)
{
    if (b == 0) 
    {
        if (terminate)
            return 0;
        
        return a / 0.000001; // Prevent crash by using a very small number
    }

    return a / b;
}

int main()
{
    std::cout << divide(10, 2) << std::endl;        // Normal division
    std::cout << divide(10, 0) << std::endl;        // Default behavior (error)
    std::cout << divide(10, 0, false) << std::endl; // Forced division
}

The divide() function divides one number by another. If the denominator (b) is zero:

terminate = true → returns 0
terminate = false → divides by a tiny number to avoid an error

The terminate parameter has a default value of true, so it can be omitted. Set terminate = false to continue the calculation instead of stopping.

Note

It is important that all default arguments are located after the positional ones in the list of parameters. Otherwise, the compiler will throw an error.

Var allt tydligt?

Tack för dina kommentarer!

Avsnitt 2. Kapitel 1