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In general function names have the same rules for variables, so they must begin with a letter or an

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underscore and cannot contain spaces or other punctuation characters here.

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So now I'm going to write some functions.

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Integer My function here, an integer like my function.

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And when we do the integer it here.

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This is the illegal and the compiler compiler will or will not compile here will not compile.

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Here.

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And.

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Uh, as I said earlier, they must begin with a letter or an underscore character and cannot contain

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spaces, as you can see here or other punctuation characters, for example, like dot comma here, they

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cannot contain any punctuation characters for.

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So following the general principle of Self-documenting code, you should name the function according

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to what it does.

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So there is one exception, and these are the special functions used to provide overloads for operators,

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which is mostly punctuation symbols.

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So these functions have a name in the form here, for example, the multi-year where the.

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Mold is like describing the function which will will multiply the two values one by one.

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So operators are one example of overloading here.

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So you can overload any function that is use the same name, but provide implementations with different

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parameter types or different parameter numbers.

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We can make it like that, for example, integer multi-year.

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We can make multiply.

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We we can multiply three numbers one by one here, for example, l h s integer r h s.

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If you make it like that or just make it integer, for example.

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Actually they will return the same value.

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This is just a different writing in C plus plus here.

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As you can see, we're going to get error because they are the two same function.

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As you can see the redefinition of multi year, multi, multi year.

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So if we make add another parameter integer x x, we're going to make the overloading function here

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and we're going to return the return, the multiply by an error and multiply in multiply it by the X

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age s here.

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And if you make it like that as standard C out.

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See out here and here.

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The most we're going to multiply.

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We're going to call this here 8 or 910.

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So in this case, uh, the multiply function will, uh, this code here, this code will call this function

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because this takes parameters and we gave this function two parameters.

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If we make it like that, uh, this is going to call the, uh, the third function.

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The second function here that we have three parameters and we are calling this function.

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So, and this named the function overloading here.

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As you can see here, we multiplied the three numbers one by one here.

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So.

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Uh, we have function parameters.

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The function here, they may not have any parameters like this here.

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For example, we can create a function with that parameters like this.

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But they let's return create without parameters, but we'll have the return value.

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So in which case the case is the function is the fate defined with a pair of empty parentheses.

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Uh, like this here, for example.

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So a function.

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The function definition must give the type and name of the parentheses parameters between parentheses

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like this here.

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So.

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And, uh, in many cases the functions will have a fixed number of parameters.

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But you can write functions with a variable number of parameters.

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So you can also define functions with the default values or some of the parentheses.

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So some of the parameters.

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So in effect a providing a function that overloads itself on the number of parameters parameters passed

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to the function.

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So variable argument list and default arguments will be covered later in this course.

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Here we can also make the make the specify the exceptions in C plus plus function here.

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The functions also can be marked to indicate whether they will throw an exception.

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So more details about exceptions will be given in next lecture.

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But there are two syntaxes you need to be aware of.

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So earlier versions of C plus plus allowed you to use the trough specifier.

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Uh, specified on the function in three ways.

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Firstly, you provide a comma separated list of types of the exceptions that may be thrown by code in

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the function here.

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The second you can provide an ellipsis like this.

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Here.

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Lapses or which means that the function may throw an exception.

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And thirdly, you can provide an empty pair of parentheses, which means that the function will not

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throw an exception.

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So the syntax here.

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Throwing exceptions to exceptions looks like this.

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For example, throw we're going to specify the exceptions.

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For example overflow overflow error and.

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Do.

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We're going to make, for example, do something which potentially.

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May overflow flow.

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So the trough specifier has been deprecated in C plus plus 11.

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As you can see, the compiler will say the dynamic exception specifier, uh, overflow error is deprecated.

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Consider using noexcept files instead.

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Here we can change ignore accept files so it throws specifier has been deprecated in C plus.

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Plus is largely because the ability to indicate that the type of function was not useful.

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So however, the version of throw that indicates that no exception will be thrown was found to be useful

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because it enables the compiler to optimize code by providing no code infrastructure to handle exceptions

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here, exceptions here.

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So the C plus plus 11 retains this behavior with no accept specifier and the no accept specifier.

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Here we can delete this false here and add with no accept specifier.

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We're going to check.

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Check the parameter and handle overflow appropriately.

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Here.