A.
Given code:
//Include necessary header files
#include <stdio.h>
#include "csapp.h"
//Define a main function
int main()
{
//Variable declaration
int status;
pid_t pid;
//Print the statement
printf("Hello\n");
//Call the method fork() and assign it to the variable pid
pid = fork();
//Print the statement
printf("%d\n",!pid);
//Check, pid is not equal to zero
if (pid != 0)
{
//True, check the condition
if (waitpid(-1, &status, 0) > 0)
{
//True, check the condition
if (WIFEXITED(status) != 0)
//True, print the statement
printf("%d\n" , WEXITSTATUS(status));
}
}
//Otherwise, print the statement
printf("Bye\n");
//Exit
exit(2);
}
Explanation:
The given code is used to print the number of output lines and possible outputs.
In the given code, the variable “status” and “pid_t pid” are declared.
- The main program first print the output line “Hello”.
- Then, call the function “fork()”, which is called once and return twice.
- Print the value that is not equal to the variable “pid”.
- The “if” condition check, the variable “pid” is not equal to “0”.
- True, “if” condition check, “(waitpid(-1, &status, 0) > 0)”.
- True, “if” condition check, “(WIFEXITED(status) != 0)”.
- True, print the value of “WEXITSTATUS(status)”.
- True, “if” condition check, “(WIFEXITED(status) != 0)”.
- True, “if” condition check, “(waitpid(-1, &status, 0) > 0)”.
- Print the statement “Bye”.
- Exit from the program.
B.
Explanation of Solution
Possible ordering of the output lines:
Possible output sequence corresponding to the process graph is as follows:
Hello
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