Dec 21, 2008 C Tutorial - 17 - The if Statement thenewboston. Unsubscribe from thenewboston? How to use the IF function in Excel 2016 - Duration: 8:36. Bob Flisser 189,720 views.
- Dev-C uses an old version of the MinGW compiler. Using a newer version of gcc from the MinGW project that supports the extended initializer lists feature of C0x (specifically the 4.4 series of gcc) should complain with a warning about the lines that are marked as erroneous.
- In the add function I want it to move on to the part where it actually adds the word only if the search function returns false (meaning it did not find the word) and I can't figure out how to express this correctly. Edit: I copied and pasted this all from emacs and the formatting is funky, don't hate.
- Apr 27, 2015 Dev-C is looking for translators, because the author doesn't master all thirty languages Dev-C is (partially) translated in. So, if you're willing to translate Dev-C into a language or update the existing translation, don't hesitate to open up YourLanguage.lng and start translating/updating, using English.lng as the reference language.
- Jan 30, 2011 gotoxy is a standard C function defined in, but it will not work in ANSI C compilers such as Dev-C. Because gotoxy is a Turbo-C specific function, which means it is not part of the standard. However, if you insist on using console functions, you can define your own function by using member functions available in.
- C++ Basics
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A function is a group of statements that together perform a task. Every C++ program has at least one function, which is main(), and all the most trivial programs can define additional functions.
You can divide up your code into separate functions. How you divide up your code among different functions is up to you, but logically the division usually is such that each function performs a specific task.
A function declaration tells the compiler about a function's name, return type, and parameters. A function definition provides the actual body of the function.
The C++ standard library provides numerous built-in functions that your program can call. For example, function strcat() to concatenate two strings, function memcpy() to copy one memory location to another location and many more functions.
A function is known with various names like a method or a sub-routine or a procedure etc.
Defining a Function
The general form of a C++ function definition is as follows −
A C++ function definition consists of a function header and a function body. Here are all the parts of a function −
- Return Type − A function may return a value. The return_type is the data type of the value the function returns. Some functions perform the desired operations without returning a value. In this case, the return_type is the keyword void.
- Function Name − This is the actual name of the function. The function name and the parameter list together constitute the function signature.
- Parameters − A parameter is like a placeholder. When a function is invoked, you pass a value to the parameter. This value is referred to as actual parameter or argument. The parameter list refers to the type, order, and number of the parameters of a function. https://high-poweraccu969.weebly.com/serum-crack-2018.html. Parameters are optional; that is, a function may contain no parameters.
- Function Body − The function body contains a collection of statements that define what the function does.
Example
Following is the source code for a function called max(). This function takes two parameters num1 and num2 and return the biggest of both −
Function Declarations
A function declaration tells the compiler about a function name and how to call the function. The actual body of the function can be defined separately.
A function declaration has the following parts −
For the above defined function max(), following is the function declaration −
Parameter names are not important in function declaration only their type is required, so following is also valid declaration −
Function declaration is required when you define a function in one source file and you call that function in another file. In such case, you should declare the function at the top of the file calling the function.
Calling a Function
While creating a C++ function, you give a definition of what the function has to do. To use a function, you will have to call or invoke that function.
When a program calls a function, program control is transferred to the called function. https://high-poweraccu969.weebly.com/download-dev-c-for-windows-8-full-version.html. A called function performs defined task and when it’s return statement is executed or when its function-ending closing brace is reached, it returns program control back to the main program.
To call a function, you simply need to pass the required parameters along with function name, and if function returns a value, then you can store returned value. For example −
I kept max() function along with main() function and compiled the source code. While running final executable, it would produce the following result −
Function Arguments
If a function is to use arguments, it must declare variables that accept the values of the arguments. These variables are called the formal parameters of the function.
The formal parameters behave like other local variables inside the function and are created upon entry into the function and destroyed upon exit.
Roland tr 909. While calling a function, there are two ways that arguments can be passed to a function − C++ add dll to project.
Sr.No | Call Type & Description |
---|---|
1 | Call by Value This method copies the actual value of an argument into the formal parameter of the function. In this case, changes made to the parameter inside the function have no effect on the argument. |
2 | Call by Pointer This method copies the address of an argument into the formal parameter. Inside the function, the address is used to access the actual argument used in the call. This means that changes made to the parameter affect the argument. |
3 | Call by Reference This method copies the reference of an argument into the formal parameter. Inside the function, the reference is used to access the actual argument used in the call. This means that changes made to the parameter affect the argument. |
By default, C++ uses call by value to pass arguments. In general, this means that code within a function cannot alter the arguments used to call the function and above mentioned example while calling max() function used the same method.
Default Values for Parameters
When you define a function, you can specify a default value for each of the last parameters. This value will be used if the corresponding argument is left blank when calling to the function.
This is done by using the assignment operator and assigning values for the arguments in the function definition. If a value for that parameter is not passed when the function is called, the default given value is used, but if a value is specified, this default value is ignored and the passed value is used instead. Consider the following example −
When the above code is compiled and executed, it produces the following result −
In C++, a function is a group of statements that is given a name, and which can be called from some point of the program. The most common syntax to define a function is:
type name ( parameter1, parameter2, ..) { statements }
Where:
-
type
is the type of the value returned by the function.-
name
is the identifier by which the function can be called.-
parameters
(as many as needed): Each parameter consists of a type followed by an identifier, with each parameter being separated from the next by a comma. Each parameter looks very much like a regular variable declaration (for example: int x
), and in fact acts within the function as a regular variable which is local to the function. The purpose of parameters is to allow passing arguments to the function from the location where it is called from.-
statements
is the function's body. It is a block of statements surrounded by braces { } that specify what the function actually does.Let's have a look at an example:
This program is divided in two functions:
addition
and main
. Remember that no matter the order in which they are defined, a C++ program always starts by calling main
. In fact, main
is the only function called automatically, and the code in any other function is only executed if its function is called from main
(directly or indirectly).In the example above,
main
begins by declaring the variable z
of type int
, and right after that, it performs the first function call: it calls addition
. The call to a function follows a structure very similar to its declaration. In the example above, the call to addition
can be compared to its definition just a few lines earlier:The parameters in the function declaration have a clear correspondence to the arguments passed in the function call. The call passes two values,
5
and 3
, to the function; these correspond to the parameters a
and b
, declared for function addition
.At the point at which the function is called from within main, the control is passed to function
addition
: here, execution of main
is stopped, and will only resume once the addition
function ends. At the moment of the function call, the value of both arguments (5
and 3
) are copied to the local variables int a
and int b
within the function.Then, inside
addition
, another local variable is declared (int r
), and by means of the expression r=a+b
, the result of a
plus b
is assigned to r
; which, for this case, where a
is 5 and b
is 3, means that 8 is assigned to r
.The final statement within the function:
Ends function
addition
, and returns the control back to the point where the function was called; in this case: to function main
. At this precise moment, the program resumes its course on main
returning exactly at the same point at which it was interrupted by the call to addition
. But additionally, because addition
has a return type, the call is evaluated as having a value, and this value is the value specified in the return statement that ended addition
: in this particular case, the value of the local variable r
, which at the moment of the return
statement had a value of 8.Therefore, the call to
addition
is an expression with the value returned by the function, and in this case, that value, 8, is assigned to z
. It is as if the entire function call (addition(5,3)
) was replaced by the value it returns (i.e., 8).Then main simply prints this value by calling:
A function can actually be called multiple times within a program, and its argument is naturally not limited just to literals:
Similar to the
addition
function in the previous example, this example defines a subtract
function, that simply returns the difference between its two parameters. This time, main
calls this function several times, demonstrating more possible ways in which a function can be called.Let's examine each of these calls, bearing in mind that each function call is itself an expression that is evaluated as the value it returns. Again, you can think of it as if the function call was itself replaced by the returned value:
If we replace the function call by the value it returns (i.e., 5), we would have:
With the same procedure, we could interpret:
as:
since 5 is the value returned by
subtraction (7,2)
.In the case of:
The arguments passed to subtraction are variables instead of literals. That is also valid, and works fine. The function is called with the values
x
and y
have at the moment of the call: 5 and 3 respectively, returning 2 as result. The fourth call is again similar:
The only addition being that now the function call is also an operand of an addition operation. Again, the result is the same as if the function call was replaced by its result: 6. Note, that thanks to the commutative property of additions, the above can also be written as:
With exactly the same result. Note also that the semicolon does not necessarily go after the function call, but, as always, at the end of the whole statement. Again, the logic behind may be easily seen again by replacing the function calls by their returned value:
Functions with no type. The use of void
The syntax shown above for functions:type name ( argument1, argument2 ..) { statements }
Requires the declaration to begin with a type. This is the type of the value returned by the function. But what if the function does not need to return a value? In this case, the type to be used is
void
, which is a special type to represent the absence of value. For example, a function that simply prints a message may not need to return any value:void
can also be used in the function's parameter list to explicitly specify that the function takes no actual parameters when called. For example, printmessage
could have been declared as:In C++, an empty parameter list can be used instead of
void
with same meaning, but the use of void
in the argument list was popularized by the C language, where this is a requirement.Something that in no case is optional are the parentheses that follow the function name, neither in its declaration nor when calling it. And even when the function takes no parameters, at least an empty pair of parentheses shall always be appended to the function name. See how
printmessage
was called in an earlier example:The parentheses are what differentiate functions from other kinds of declarations or statements. The following would not call the function:
The return value of main
You may have noticed that the return type ofmain
is int
, but most examples in this and earlier chapters did not actually return any value from main
.Well, there is a catch: If the execution of
main
ends normally without encountering a ![C++ functions pdf C++ functions pdf](/uploads/1/2/6/2/126216104/328864870.jpg)
return
If Function In Dev C File
![C++ functions pdf C++ functions pdf](/uploads/1/2/6/2/126216104/590458403.png)
Note that this only applies to function
main
for historical reasons. All other functions with a return type shall end with a proper return
statement that includes a return value, even if this is never used.When
main
returns zero (either implicitly or explicitly), it is interpreted by the environment as that the program ended successfully. Other values may be returned by main
, and some environments give access to that value to the caller in some way, although this behavior is not required nor necessarily portable between platforms. The values for main
that are guaranteed to be interpreted in the same way on all platforms are:value | description |
---|---|
0 | The program was successful |
EXIT_SUCCESS | The program was successful (same as above). This value is defined in header '><cstdlib> . |
EXIT_FAILURE | The program failed. This value is defined in header '><cstdlib> . |
Because the implicit
return 0;
statement for main
is a tricky exception, some authors consider it good practice to explicitly write the statement.Dev C++ Programs
Arguments passed by value and by reference
In the functions seen earlier, arguments have always been passed by value. This means that, when calling a function, what is passed to the function are the values of these arguments on the moment of the call, which are copied into the variables represented by the function parameters. For example, take:In this case, function addition is passed 5 and 3, which are copies of the values of
x
and y
, respectively. These values (5 and 3) are used to initialize the variables set as parameters in the function's definition, but any modification of these variables within the function has no effect on the values of the variables x and y outside it, because x and y were themselves not passed to the function on the call, but only copies of their values at that moment.In certain cases, though, it may be useful to access an external variable from within a function. To do that, arguments can be passed by reference, instead of by value. For example, the function
duplicate
in this code duplicates the value of its three arguments, causing the variables used as arguments to actually be modified by the call:To gain access to its arguments, the function declares its parameters as references. In C++, references are indicated with an ampersand (
&
) following the parameter type, as in the parameters taken by duplicate
in the example above.When a variable is passed by reference, what is passed is no longer a copy, but the variable itself, the variable identified by the function parameter, becomes somehow associated with the argument passed to the function, and any modification on their corresponding local variables within the function are reflected in the variables passed as arguments in the call.
In fact,
a
, b
, and c
become aliases of the arguments passed on the function call (x
, y
, and z
) and any change on a
within the function is actually modifying variable x
outside the function. Any change on b
modifies y
, and any change on c
modifies z
. That is why when, in the example, function duplicate
modifies the values of variables a
, b
, and c
, the values of x
, y
, and z
are affected.If instead of defining duplicate as:
Was it to be defined without the ampersand signs as:
The variables would not be passed by reference, but by value, creating instead copies of their values. In this case, the output of the program would have been the values of
x
, y
, and z
without being modified (i.e., 1, 3, and 7).Efficiency considerations and const references
Calling a function with parameters taken by value causes copies of the values to be made. This is a relatively inexpensive operation for fundamental types such asint
, but if the parameter is of a large compound type, it may result on certain overhead. For example, consider the following function:This function takes two strings as parameters (by value), and returns the result of concatenating them. By passing the arguments by value, the function forces
a
and b
to be copies of the arguments passed to the function when it is called. And if these are long strings, it may mean copying large quantities of data just for the function call.But this copy can be avoided altogether if both parameters are made references:
Arguments by reference do not require a copy. The function operates directly on (aliases of) the strings passed as arguments, and, at most, it might mean the transfer of certain pointers to the function. In this regard, the version of
concatenate
taking references is more efficient than the version taking values, since it does not need to copy expensive-to-copy strings.On the flip side, functions with reference parameters are generally perceived as functions that modify the arguments passed, because that is why reference parameters are actually for.
The solution is for the function to guarantee that its reference parameters are not going to be modified by this function. This can be done by qualifying the parameters as constant:
By qualifying them as
const
, the function is forbidden to modify the values of neither a
nor b
, but can actually access their values as references (aliases of the arguments), without having to make actual copies of the strings.Therefore,
const
references provide functionality similar to passing arguments by value, but with an increased efficiency for parameters of large types. That is why they are extremely popular in C++ for arguments of compound types. Note though, that for most fundamental types, there is no noticeable difference in efficiency, and in some cases, const references may even be less efficient!If Function In Dev C Pdf
Inline functions
Calling a function generally causes a certain overhead (stacking arguments, jumps, etc..), and thus for very short functions, it may be more efficient to simply insert the code of the function where it is called, instead of performing the process of formally calling a function.Preceding a function declaration with the
inline
specifier informs the compiler that inline expansion is preferred over the usual function call mechanism for a specific function. This does not change at all the behavior of a function, but is merely used to suggest the compiler that the code generated by the function body shall be inserted at each point the function is called, instead of being invoked with a regular function call.For example, the concatenate function above may be declared inline as:
This informs the compiler that when
concatenate
is called, the program prefers the function to be expanded inline, instead of performing a regular call. inline
is only specified in the function declaration, not when it is called.Note that most compilers already optimize code to generate inline functions when they see an opportunity to improve efficiency, even if not explicitly marked with the
inline
specifier. Therefore, this specifier merely indicates the compiler that inline is preferred for this function, although the compiler is free to not inline it, and optimize otherwise. In C++, optimization is a task delegated to the compiler, which is free to generate any code for as long as the resulting behavior is the one specified by the code.Default values in parameters
In C++, functions can also have optional parameters, for which no arguments are required in the call, in such a way that, for example, a function with three parameters may be called with only two. For this, the function shall include a default value for its last parameter, which is used by the function when called with fewer arguments. For example:In this example, there are two calls to function
divide
. In the first one:The call only passes one argument to the function, even though the function has two parameters. In this case, the function assumes the second parameter to be 2 (notice the function definition, which declares its second parameter as
int b=2
). Therefore, the result is 6.In the second call:
The call passes two arguments to the function. Therefore, the default value for
b
(int b=2
) is ignored, and b
takes the value passed as argument, that is 4, yielding a result of 5.Declaring functions
In C++, identifiers can only be used in expressions once they have been declared. For example, some variablex
cannot be used before being declared with a statement, such as:The same applies to functions. Functions cannot be called before they are declared. That is why, in all the previous examples of functions, the functions were always defined before the
main
function, which is the function from where the other functions were called. If main
were defined before the other functions, this would break the rule that functions shall be declared before being used, and thus would not compile.The prototype of a function can be declared without actually defining the function completely, giving just enough details to allow the types involved in a function call to be known. Naturally, the function shall be defined somewhere else, like later in the code. But at least, once declared like this, it can already be called.
The declaration shall include all types involved (the return type and the type of its arguments), using the same syntax as used in the definition of the function, but replacing the body of the function (the block of statements) with an ending semicolon.
The parameter list does not need to include the parameter names, but only their types. Parameter names can nevertheless be specified, but they are optional, and do not need to necessarily match those in the function definition. For example, a function called
protofunction
with two int parameters can be declared with either of these statements:Anyway, including a name for each parameter always improves legibility of the declaration.
This example is indeed not an example of efficiency. You can probably write yourself a version of this program with half the lines of code. Anyway, this example illustrates how functions can be declared before its definition:
The following lines:
Declare the prototype of the functions. They already contain all what is necessary to call them, their name, the types of their argument, and their return type (
void
in this case). With these prototype declarations in place, they can be called before they are entirely defined, allowing for example, to place the function from where they are called (main
) before the actual definition of these functions.But declaring functions before being defined is not only useful to reorganize the order of functions within the code. In some cases, such as in this particular case, at least one of the declarations is required, because
odd
and even
are mutually called; there is a call to even
in odd
and a call to odd
in even
. And, therefore, there is no way to structure the code so that odd
is defined before even
, and even
before odd
.Recursivity
Recursivity is the property that functions have to be called by themselves. It is useful for some tasks, such as sorting elements, or calculating the factorial of numbers. For example, in order to obtain the factorial of a number (n!
) the mathematical formula would be:n! = n * (n-1) * (n-2) * (n-3) .. * 1
More concretely,
5!
(factorial of 5) would be:5! = 5 * 4 * 3 * 2 * 1 = 120
And a recursive function to calculate this in C++ could be:
Notice how in function factorial we included a call to itself, but only if the argument passed was greater than 1, since, otherwise, the function would perform an infinite recursive loop, in which once it arrived to 0, it would continue multiplying by all the negative numbers (probably provoking a stack overflow at some point during runtime).
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