Fork and Pipe

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <string.h>
#include<unistd.h>
int main()
{int menu = 0;
printf("\n\n\n");
printf("************************ Code By ******************** \n");
printf(" avb\n");
printf("********************* WELCOME *********************** \n"); 
do
{
printf("\n\n");
printf("1. Create and write a File \n");
printf("2. Read from a File\n");
printf("3. Pipe\n");
printf("4. dup2\n");
printf("5. Fork\n");
printf("6. To exit from the program\n");
printf("Hello User please Enter your choice =");

scanf("%d", &menu); 
switch 
(menu) 
{
case 1:
{
FILE *fptr;
char name[20];
int age;
float salary;
fptr = fopen ("emp.rec", "w"); /*open for writing*/
if (fptr == NULL)
{
printf("File does not exists\n");
return;
}
printf("Enter the name\n");
scanf("%s", name);
fprintf(fptr, "Name = %s\n", name);
printf("Enter the age\n");
scanf("%d", &age);
fprintf(fptr, "Age = %d\n", age);
printf("Enter the salary\n");
scanf("%f", &salary);
fprintf(fptr, "Salary = %.2f\n", salary);
fclose(fptr);
break;
}
case 2:
{
FILE * pFile;
char ch, file_name [250];
pFile = fopen ("emp.rec" , "r");
if (pFile == NULL) perror ("Error opening file");else {

printf("The contents of %s file are :\n", file_name);
while( ( ch = fgetc(pFile) ) != EOF )
printf("%c",ch);fclose(pFile);
}

break;
} 
case 3:
{
void write_to_pipe (int file)
{
FILE *stream;
stream = fdopen (file, "w");
fprintf (stream, "hello, world!\n");
fprintf (stream, "goodbye, world!\n");
fclose (stream);
}
void read_from_pipe (int file)
{
FILE *stream;
int c;
stream = fdopen (file, "r");
while ((c = fgetc (stream)) != EOF)
putchar (c);
fclose (stream);
}
pid_t pid;
int mypipe[2];
/* Create the pipe. */
if (pipe (mypipe))
{
fprintf (stderr, "Pipe failed.\n");
// return EXIT_FAILURE;
}
/* Create the child process. */
pid = fork ();
if (pid == (pid_t) 0)
{
/* This is the child process.
Close other end first. */
close (mypipe[1]);
read_from_pipe (mypipe[0]);
// return EXIT_SUCCESS;
}
else if (pid < (pid_t) 0)
{
/* The fork failed. */
fprintf (stderr, "Fork failed.\n");
return EXIT_FAILURE;
}
else
{
/* This is the parent process.
Close other end first. */
close (mypipe[0]);
write_to_pipe (mypipe[1]);
//return EXIT_SUCCESS;}

break;
}case 4
{

//First, we're going to open a file
int file = open("myfile.txt", O_APPEND | O_WRONLY);
if(file < 0) return 1;//Now we redirect standard output to the file using dup2
if(dup2(file,1) < 0) return 1;

//Now standard out has been redirected, we can write to
// the file
printf( "This will print in myfile.txt\n" ); return 0;

break;
}//end of function main
case 5:
{

{
int i = 1;
pid_t child_pid;
printf("The main program process ID is %d", (int) getpid());
printf("%d", i);
child_pid = fork();
if (child_pid != 0) {
i++;
printf("%d", i);
printf("This is the parent process, with ID %d \n", (int) getpid());
printf("The child process is %d ", (int) child_pid);
}
 else 
{
printf("%d", i);
printf("This is the child process, with ID %d \n", (int) getpid());
}
}
return 1;
break; 
}
default;
{printf("You are out of prog\n");

} 
}
}while(menu!=6);
return 0;
}