answersLogoWhite

0

Formal and Actual Arguments

Updated: 8/11/2023
User Avatar

Wiki User

13y ago

Best Answer

The actual arguments (we call them parameters) to a function are the original copies in the caller's address space. The function prolog code provided by the compiler provides for making copies of all of the parameters. These copies are called the formal parameters. In C and C++, the default calling convention is call by value, which means that the called function only has access to the formal copy. Optionally, you can call by reference, passing instead the address of the actual parameter. Using dereference notation, the called function then has access to the actual parameter, and the formal parameter is simply its address.

One of the things that sometimes confuses people is the name of the parameter. You might, for instance, call something alpha in you main function. It is called alpha, and alpha means the memory location of alpha. In the function, however, you can call the parameter something else, perhaps beta. Within the context of the called function, beta contains the value of or the address of alpha, but it is not alpha, it is beta. To make matters worse, you can have another alpha within a block, or within the function, and that is certainly not related at all to the original alpha.

Recommendation: Always call an object by consistent names. This way, you won't get into scoping rules trouble.

User Avatar

Wiki User

13y ago
This answer is:
User Avatar
More answers
User Avatar

Wiki User

8y ago

Actual arguments are the arguments you pass to a function while formal arguments are the arguments used by the function. The value of an actual argument is assigned to its corresponding formal argument unless the formal argument is a reference in which case the address of the actual argument is passed. Arguments are passed to functions by pushing their values onto the call stack prior to passing control to the function. When the function gains control, the values are popped from the stack and assigned to the appropriate formal arguments.

This answer is:
User Avatar

User Avatar

Wiki User

10y ago

Formal Arguments: The arguments which declares your function, use of the function.

Actual Arguments: The arguments where the function is being used.

Example:

#include<stdio.h>

#include<conio.h>

int sum(int x, int y)//formal Argument

{

int z;

z=x+y;

printf("%d",z);

}

void main()

{

int d;

printf("Enter any number\n");

scanf("%d",d);

sum(d);//actual argument

getch();

}

This answer is:
User Avatar

Add your answer:

Earn +20 pts
Q: Formal and Actual Arguments
Write your answer...
Submit
Still have questions?
magnify glass
imp
Continue Learning about Engineering

Can both actual and formal arguments can have the same name?

Yes, they can.


What is the difference between actual and formal argument in c plus plus?

Formal parameters are the parameters as they are known in the function definition. Actual parameters (also known as arguments) are what are passed by the caller. For example, in the following code, a and b are the formal parameters, and x and y are the actual parameters:int max(int a, int b) {if (a > b) return a;else return b;}int m = max(x, y);


Explain the difference between an argument and a parameter Use a C plus plus program segment to illustrate your answer?

In C++ there is no such thing as a parameter, there are only arguments, both actual and formal. Some languages use the term parameter to mean a formal argument and argument to mean an actual argument, while others reverse the meanings completely. Some languages make no distinction at all and use the terms parameter and argument interchangeably. However, C++ is quite clear on this: actual arguments are the names that you pass to a function, while formal arguments are the names received by the function. Even so, you will still encounter incorrect usage of the terms parameter and arguments, even by C++ experts (myself included!) The following example code demonstrates the difference between an actual argument and a formal argument, as the terms apply in C++: int foo(int formal) { return(formal*2); } void bar(int&amp; formal) { formal*=2; } int main() { int actual=1; actual = foo(actual); bar(actual); return(0); } The function foo() declares a formal argument by value while bar() declares a formal argument by reference. In main() we declare a variable with the name actual and pass this actual argument to both functions in turn. When we pass actual to foo(), the value of actual is assigned to formal. Since formal is a copy of actual, they are separate names with separate values (initially they will have the same value of course). Thus any changes made to formal will have no effect on actual, hence we must assign the return value from foo() to actual in main(), in order to record the change made by foo(). When we pass actual to bar(), a reference to actual is assigned to formal. A reference is simply an alternate name for the same argument, however the name actual is not visible to bar(), so they are still separate names, but they always have the same value. Thus any changes to formal will affect actual, thus there is no need to assign any return value to record the change.


In python are actual and formal parameters matched up by position or name?

When we invoke a function, we pass the actual arguments in the same order specified by the function's formal arguments, thus it is the relative position that determines how they are matched. Note that actual parameter names are within the scope of the calling code while formal parameter names are scoped to the function in which they are declared. The calling code has no access to the formal argument names, and the function may or may not have access to the actual argument names. Python uses the pass-by-object paradigm: if the object being passed is immutable, then it is passed by value (the formal parameter is assigned a copy of the object's value), otherwise it is passed by reference (in which case the formal argument becomes an alternative name for the actual argument).


What is meant by arguments in c?

Arguments appear in functions and in function calls. Arguments passed to a function are known as actual arguments. The arguments used by the function are known as the formal arguments. In C, all arguments are passed by value, such that the formal argument is a copy of the actual argument.

Related questions

What are the formal arguments?

Formal arguments are the named arguments defined by the function. Actual arguments are those arguments that were passed to the function by the caller.


Can both actual and formal arguments can have the same name?

Yes, they can.


What is the difference between actual and formal argument in c plus plus?

Formal parameters are the parameters as they are known in the function definition. Actual parameters (also known as arguments) are what are passed by the caller. For example, in the following code, a and b are the formal parameters, and x and y are the actual parameters:int max(int a, int b) {if (a > b) return a;else return b;}int m = max(x, y);


Why the actual arguments declared as float is accepted only as double in formal arguments in java?

Sorry I don't Think I could Solve It


Relationship between actual and formal arguments?

The formal arguments are the names given to the parameters/arguments in the function declaration. These names will be used within the body of the function. void myFunc( int i, char c ); // Function prototype The actual arguments are the variables and/or constants (those supplied by the caller) that are used when invoking the function. int intVar = 6; char charVar = 'e'; // Actual parameters 3 and 'G' will be mapped to the // formal parameters 'i' and 'c' myFunc( 3, 'G' ); // Execute function // Actual parameters 'intVar' and 'charVar' will be mapped // to the formal parameters 'i' and 'c' myFunc( intVar, charVar ); // Execute function


Sample program in c plus plus with parameter?

C++ doesn't have parameters it has arguments, both formal and actual. Actual arguments are the arguments you pass to a function. Formal arguments are the arguments used by the function and which are treated as local variables within the function body. Formal arguments always fall from scope when the function returns. In order for a function to make changes to the actual argument you you can either return the formal argument by value and assign the function to the actual argument upon return, or you can pass the argument by reference. In the former case, the returned value is temporary. If the function is not assigned to the actual argument, the temporary value falls from scope. In the latter case, the actual and formal arguments both refer to the same object through separate names (aliases). Thus any operations performed on the formal argument will affect the actual argument (they are one and the same object). Example: // Forward declarations. int byval (int); void byref (int&amp;); int main() { int actual = 42; byval (actual); // The byval formal argument is no longer in scope. // Although a temporary value of 84 was returned, // it wasn't assigned to anything and is no longer // available. // The actual argument still has the value 42. actual = byval (actual); // The byval formal argument is no longer in scope, // however, its value was returned and assigned // to the actual argument. // The actual argument now has the value 84. byref (actual); // The formal argument and the actual argument are // one and the same argument. // The actual argument now has the value 42. } int byvalue(int formal) { formal *= 2; return formal; } // The formal argument no longer exists, but its value // was pushed into the function's return address. That // value will cease to exist unless the caller immediately // assigns the function's return value to a variable. void byref(int&amp; formal) { formal /= 2; } // The formal argument no longer exists and nothing // was pushed onto the function's return address. // However, formal was just an alias for the actual // argument, thus the actual argument has already // been updated.


Explain the difference between an argument and a parameter Use a C plus plus program segment to illustrate your answer?

In C++ there is no such thing as a parameter, there are only arguments, both actual and formal. Some languages use the term parameter to mean a formal argument and argument to mean an actual argument, while others reverse the meanings completely. Some languages make no distinction at all and use the terms parameter and argument interchangeably. However, C++ is quite clear on this: actual arguments are the names that you pass to a function, while formal arguments are the names received by the function. Even so, you will still encounter incorrect usage of the terms parameter and arguments, even by C++ experts (myself included!) The following example code demonstrates the difference between an actual argument and a formal argument, as the terms apply in C++: int foo(int formal) { return(formal*2); } void bar(int&amp; formal) { formal*=2; } int main() { int actual=1; actual = foo(actual); bar(actual); return(0); } The function foo() declares a formal argument by value while bar() declares a formal argument by reference. In main() we declare a variable with the name actual and pass this actual argument to both functions in turn. When we pass actual to foo(), the value of actual is assigned to formal. Since formal is a copy of actual, they are separate names with separate values (initially they will have the same value of course). Thus any changes made to formal will have no effect on actual, hence we must assign the return value from foo() to actual in main(), in order to record the change made by foo(). When we pass actual to bar(), a reference to actual is assigned to formal. A reference is simply an alternate name for the same argument, however the name actual is not visible to bar(), so they are still separate names, but they always have the same value. Thus any changes to formal will affect actual, thus there is no need to assign any return value to record the change.


In python are actual and formal parameters matched up by position or name?

When we invoke a function, we pass the actual arguments in the same order specified by the function's formal arguments, thus it is the relative position that determines how they are matched. Note that actual parameter names are within the scope of the calling code while formal parameter names are scoped to the function in which they are declared. The calling code has no access to the formal argument names, and the function may or may not have access to the actual argument names. Python uses the pass-by-object paradigm: if the object being passed is immutable, then it is passed by value (the formal parameter is assigned a copy of the object's value), otherwise it is passed by reference (in which case the formal argument becomes an alternative name for the actual argument).


What is meant by arguments in c?

Arguments appear in functions and in function calls. Arguments passed to a function are known as actual arguments. The arguments used by the function are known as the formal arguments. In C, all arguments are passed by value, such that the formal argument is a copy of the actual argument.


What is a sentence for formal?

You do not pass the formal arguments to the function like that. (in context with programming)You need to write a formal letter.


Why is it possible to use the same variable names for actual and formal arguments in c language?

1. Because they are completely unrelated names. 2. Because there is no rule against them having the same names.


What is an actual parameter?

A formal perimeter refers to an identifier that is used in a method to stand for the value that is passed into the method by a caller. An actual perimeter on the other hand refers to the actual value that is passed into the method by a caller.