PROGRAM – SWAP TWO NUMBERS BY CALL BY VALUE

void swap(int x, int y) {    int z;      z = x;    x = y;     y = z;    printf("Swapped values are a = %d and b = %d", x, y); } int main()   {   int a = 7, b = 4;  printf("Original values are a = %d and b = %d", a, b);  swap(a, b);   }

EXPLANATION

int main()int a=7, b=4;

int main() It is main function. Execution starts from here

int a=7 int b=4 Variables declare and values are

given

EXPLANATION• printf("Original values are a = %d and b = %d", a, b);• This will print original values • Values as a=7 and b=4

• swap(a,b);

swap(a,b) This will call swap function

Swap function is called and a, b are parameters which are passed in the function. a=7 and b=4 are passed

EXPLANATION

swap(a,b)

void swap(int x, int y)

Call swap

Pass a and b as parameters in swap function i.e.

void swap(int x, int y).a is passed as x and b as y in

void swap(int x, int y)

Swap is performed

EXPLANATION

• void swap(int x, int y)• Function declaration • Simple swap function to swap 2 numbers

swap

int x int y

Function name

void returntype

parameters

EXPLANATION void swap(int x, int y) {    int z;      z = x;    x = y;     y = z;    printf("Swapped values are a = %d and b = %d", x, y); }

int z Z is a variable of integer type

EXPLANATION

z = x;    x = y;     y = z;

z

x

y z

y

x=

=

=

Swap function

Here z is a variable and x and y are paramters which are passed in the void swap () function.

EXPLANATION

z = x;    x = y;     y = z;

z=x z=7

x=y x=4

y=7 y=z

Values swapped

EXPLANATION•  printf("Swapped values are a = %d and b = %d", x, y); We get swapped values of given values .

Original values are a=7 and b=4Swapped values are a=4 and b=7

Output of program

CALL BY VALUE FLOW DIAGRAM

• Here is the flow diagram describing disassembly steps, call stack and argument variables. Calling swap (a, b) can be split into some assembly steps like-

• push value of b• push value of a• save return address• call function• Here one point to note is x and y are in stack. Value of a and b will be

copied to x and y. Inside swap() value of x and y will be interchanged but it will not affect a and b in the main(). Please note a and b are located at the context of main() whereas x and y located at the context of swap(). When swap() function returns, this context of x and y will be lost and it will again come back to the context of a and b.

CALL BY VALUE FLOW DIAGRAM

CALL BY VALUE EXPLANATION• When passing Parameters using Call by Value,xerox copy of original

parameters is created and passed in the called function.• Any update made inside the method won’t affect the original value of

variable in calling function

THANK YOU