Question

Consider the following C program:
#include <stido.h>
void fun 1 (char *s1, char *s2) {
char *tmp
tmp = s1;
s1 = s2;
s2 = tmp;
}
void fun2 (char **s1, char **s2) {
char *tmp;
tmp = * s1;
*s1 = *s2;
*s2 = tmp;
}
int main ( ) {
char * str1 = "Hi", *str2 = "Bye";
fun1 (str1, str2); printf("%s, %s", str1, str2);
fun2 (&str1, &str2);printf("%s %s", str1, str2);
return 0;
}
The output of the program above is

• A. Hi Bye Hi Bye
• B. Bye Hi Hi Bye
• C. Hi Bye Bye Hi
• D. Bye Hi Bye Hi

Answer 1

The correct option is C Hi Bye Bye Hi


1. fun1(100, 200) "Call By Value"
*s1 = 100; *s2 = 200;
*temp = 100;
*s1 = 200;
*s2 = 100;
Since, fun1 is call by value. So no change to original *str1 and *str2, so printf will print Hi Bye
2. fun2 (&str1, &str2) "Call By Refference"
**s1 = 300; ** s2 = 400;
*temp = 300;
**s1 = 400;
** s2 = 300;
Since, fun2 is call refference. So it will swap the value of str1 and str2 points to "Hi". So printf will point Bye
Hi.
Final output: Hi Bye Bye Hi