Question

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A.4 5 pts Please explain each parameter passing method, when to use it, and code a function prototype example Pass-by-lvalue-reference Pass-by-const-rvalue-reference

Answer 1

pass-by-lvalue-reference:
Generally in this methodology we pass pointers instead of variable names so that the changes in the function will effect the variable
let us take an example
here in the following C program intially the values are a= 10 b =20
in the function we swapped the values to a = 20 b = 10
after the function calling the values of a and b are changed a = 20 b = 10
since we have passed the address the values at the addresses are changed

#include<stdio.h>
void swap(int *a,int *b)
{
   int *temp;
   *temp = *a;
   *a = *b;
   *b = *temp;
   printf("the value of a in function %d\n",*a);
   printf("the value of b in function %d\n",*b);
}
int main()
{
   int a = 10,b = 20;
   printf("the value of a before calling the function %d\n",a);
   printf("the value of b before calling the function %d\n",b);
   swap(&a,&b);
   printf("the value of a after calling the function %d\n",a);
   printf("the value of b after calling the function %d\n",b);
   return 0;
}

deepika@deepika-Travel Mate- P243-M: ~/Desktop Terminal File Edit View Search Help deepika@deepika -Travel Mate -P243 -M:~/Desktop$ gcc demo_var.c deepika@deepika -TravelMate - P243 -M : ~/ Desktop$ ./a .out the value of a before calling the function 10 the value of b before calling the function 20 the value of b in function 10 the value of a after calling the function 28 the value of b after calling the function 10 Segmentation fault deepika@deepika -T ravelMate -P243 -M :~/ Desktop$ Sat 12:05 INI

pass-by-const-rvalue-reference:
Generally in this methodology we pass variable names so that the changes in the function will not effect the variable
let us take an example
here in the following C program intially the values are a= 10 b =20
in the function we swapped the values to a = 20 b = 10
after the function calling the values of a and b are still a = 10 b = 20
since we have passed the varable names only the values are not get changed.

#include<stdio.h>
void swap(int a,int b)
{
   int temp;
   temp = a;
   a = b;
   b = temp;
   printf("the value of a in function %d\n",a);
   printf("the value of b in function %d\n",b);
}
int main()
{
   int a = 10,b = 20;
   printf("the value of a before calling the function %d\n",a);
   printf("the value of b before calling the function %d\n",b);
   swap(a,b);
   printf("the value of a after calling the function %d\n",a);
   printf("the value of b after calling the function %d\n",b);
   return 0;
}

deepika@deepika-Travel Mate- P243-M: ~/Desktop Terminal File Edit View Search Help deepika@deepika -Travel Mate -P243 -M:~/Desktop$ gcc demo_var.c deepika@deepika -TravelMate - P243 -M : ~/ Desktop$ ./a .out the value of a before calling the function 10 the value of b before calling the function 20 the value of b in function 10 the value of a after calling the function 18 the value of b after calling the function 20 deepika@deepika -TravelMate -P243 -M : ~/ Desktop$ Sat 12:06 INI

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