Difference Between Actual Parameter And Formal Paramete...

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Difference Between Actual Parameter And Formal Parameter

Actual Parameters In Java
Difference Between Actual Parameter And Formal Parameters In Java
The difference between Actual Parameters and Formal Parameters is that Actual Parameters are the values that are passed to the function when it is invoked while Formal Parameters are the variables defined by the function that receives values when the function is called. The terms 'formal argument' & 'actual argument' are synonymous to the terms 'parameters' & 'argument' respectively. I know, it sounds a little confusing, so let me explain further.
Functions can be invoked in two ways: Call by Value or Call by Reference. These two ways are generally differentiated by the type of values passed to them as parameters. 
The parameters passed to function are called actual parameters whereas the parameters received by function are called formal parameters.

Call By Value: In this parameter passing method, values of actual parameters are copied to function's formal parameters and the two types of parameters are stored in different memory locations. So any changes made inside functions are not reflected in actual parameters of the caller.
Call by Reference: Both the actual and formal parameters refer to the same locations, so any changes made inside the function are actually reflected in actual parameters of the caller.
Call By Value Call By Reference 
While calling a function, we pass values of variables to it. Such functions are known as 'Call By Values'. While calling a function, instead of passing the values of variables, we pass address of variables(location of variables) to the function known as 'Call By References. 
 In this method, the value of each variable in calling function is copied into corresponding dummy variables of the called function.  In this method, the address of actual variables in the calling function are copied into the dummy variables of the called function.
 With this method, the changes made to the dummy variables in the called function have no effect on the values of actual variables in the calling function. With this method, using addresses we would have an access to the actual variables and hence we would be able to manipulate them. 
Thus actual values of a and b remain unchanged even after exchanging the values of x and y.Thus actual values of a and b get changed after exchanging values of x and y.
 In call by values we cannot alter the values of actual variables through function calls. In call by reference we can alter the values of variables through function calls.
 Values of variables are passes by Simple technique. Pointer variables are necessary to define to store the address values of variables.

Note : In C, we use pointers to achieve call by reference. In C++, we can either use pointers or references to for pass by reference. In Java, primitive types are passed as values and non-primitive types are always references.
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The arguments may be classified under two groups, actual andformal arguments.
(a)Actual argumentsAn actual argument is a variable oran expression contained in a function call that replaces the formal parameterwhich is a part of the function declaration.
Sometimes, afunction may be called by a portion of a program with some parameters and theseparameters are known as the actual arguments. 
#include 
{
void output (int x, int y) ; // function declaration

output (x,y) ; / / x and y arethe actual arguments

Call By Value	Call By Reference
While calling a function, we pass values of variables to it. Such functions are known as 'Call By Values'.	While calling a function, instead of passing the values of variables, we pass address of variables(location of variables) to the function known as 'Call By References.
In this method, the value of each variable in calling function is copied into corresponding dummy variables of the called function.	In this method, the address of actual variables in the calling function are copied into the dummy variables of the called function.
With this method, the changes made to the dummy variables in the called function have no effect on the values of actual variables in the calling function.	With this method, using addresses we would have an access to the actual variables and hence we would be able to manipulate them.
Thus actual values of a and b remain unchanged even after exchanging the values of x and y.	Thus actual values of a and b get changed after exchanging values of x and y.
In call by values we cannot alter the values of actual variables through function calls.	In call by reference we can alter the values of variables through function calls.
Values of variables are passes by Simple technique.	Pointer variables are necessary to define to store the address values of variables.

(b)Formal argumentsFormal arguments are the parameterspresents in a function definition which may also be called as dummy argumentsor the parametric variables. When the function is invoked, the formalparameters are replaced by the actual parameters.
#include 
{
void output (int x, int y) ; 

output (x,y) ; 
void output (int a, int b)/ / formal or dummy arguments 
/ /body of the function
Formal arguments maybe declared by the same name or by different names in calling a portion of theprogram or in a called function but the data types should be the same in bothblocks.
For example, the following function declaration is invalid.
void main ()

Difference between actual parameter and formal parameters with example

Call By Value: In this parameter passing method, values of actual parameters are copied to function's formal parameters and the two types of parameters are stored in different memory locations. So any changes made inside functions are not reflected in actual parameters of the caller.
Call by Reference: Both the actual and formal parameters refer to the same locations, so any changes made inside the function are actually reflected in actual parameters of the caller.
Call By Value Call By Reference 
While calling a function, we pass values of variables to it. Such functions are known as 'Call By Values'. While calling a function, instead of passing the values of variables, we pass address of variables(location of variables) to the function known as 'Call By References. 
 In this method, the value of each variable in calling function is copied into corresponding dummy variables of the called function.  In this method, the address of actual variables in the calling function are copied into the dummy variables of the called function.
 With this method, the changes made to the dummy variables in the called function have no effect on the values of actual variables in the calling function. With this method, using addresses we would have an access to the actual variables and hence we would be able to manipulate them. 
Thus actual values of a and b remain unchanged even after exchanging the values of x and y.Thus actual values of a and b get changed after exchanging values of x and y.
 In call by values we cannot alter the values of actual variables through function calls. In call by reference we can alter the values of variables through function calls.
 Values of variables are passes by Simple technique. Pointer variables are necessary to define to store the address values of variables.

Note : In C, we use pointers to achieve call by reference. In C++, we can either use pointers or references to for pass by reference. In Java, primitive types are passed as values and non-primitive types are always references.
Attention reader! Don't stop learning now. Get hold of all the important DSA concepts with the DSA Self Paced Course at a student-friendly price and become industry ready.
Recommended Posts:If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the 'Improve Article' button below.


The arguments may be classified under two groups, actual andformal arguments.
(a)Actual argumentsAn actual argument is a variable oran expression contained in a function call that replaces the formal parameterwhich is a part of the function declaration.
Sometimes, afunction may be called by a portion of a program with some parameters and theseparameters are known as the actual arguments. 
#include 
{
void output (int x, int y) ; // function declaration

output (x,y) ; / / x and y arethe actual arguments
(b)Formal argumentsFormal arguments are the parameterspresents in a function definition which may also be called as dummy argumentsor the parametric variables. When the function is invoked, the formalparameters are replaced by the actual parameters.
#include 
{
void output (int x, int y) ; 

output (x,y) ; 
void output (int a, int b)/ / formal or dummy arguments 
/ /body of the function
Formal arguments maybe declared by the same name or by different names in calling a portion of theprogram or in a called function but the data types should be the same in bothblocks.
For example, the following function declaration is invalid.
void main ()
void funct (int x, int y, char s1,char s2) ;
char s1, s2;
Actual Parameters In Java
}
funct (char c1, char c2, int a, int b) // data type mismatch 
/ / body of a function
Difference Between Actual Parameter And Formal Parameters In Java