Question

Write the half function. A function call and the functionprototype

Answer 1

Answer:

C code for half()

#include<stdio.h>

void half(float *pv);

int main()

{

float value=5.0;  //value is initialized  

printf ("Value before half: %4.1f\n", value); // Prints 5.0

half(&value);  // the function call takes the address of the variable.

printf("Value after half: %4.1f\n", value); // Prints 2.5

}

void half(float *pv) //In function definition pointer pv will hold the address of variable passed.

{

*pv=*pv/2;  //pointer value is accessed through * operator.

}

• This method is called call-by-reference method.

• Here when we call a function, we pass the address of the variable instead of passing the value of the variable.

• The address of “value” is passed from the “half” function within main(), then in called “half” function we store the address in float pointer ‘pv.’ Now inside the half(),  we can manipulate the value pointed by pointer ‘pv’. That will reflect in the main().

• Inside half() we write *pv=*pv/2, which means the value of variable pointed by ‘pv’ will be the half of its value, so after returning from half function value of variable “value” inside main will be 2.5.

Output:

Output is given as image.