I tried to allocate some memory in parent and tried to pass pointer to that memory to child and child to change value of it by double-ptr-de-referencing but it failed. it access the value and shows value correctly but when it's changed parent cant still get change in variable's value.
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <dirent.h>
int main() {
int pipeVariable[2] = {0};
pipe(pipeVariable);
int x = fork();
if(x == -1){
perror("Error spawning child process");
exit(1);
}
else if(x == 0){
int *value = NULL;
read(pipeVariable[0], value, sizeof(int));
printf("Child \nMemory block : %p\nValue : %d\n", value, *value);
printf("Child Changed the value\n");
*value = 10;
printf("Child \nMemory block : %p\nValue : %d\n", value, *value);
close(pipeVariable[1]);
close(pipeVariable[0]);
exit(0);
}
else{
int *testVariable = malloc(sizeof(int));
*testVariable = 1000;
printf("Parent \nMemory block : %p\nValue : %d\n", testVariable, *testVariable);
write(pipeVariable[1], testVariable, sizeof(int));
wait(NULL);
printf("Parent \nMemory block : %p\nValue : %d\n", testVariable, *testVariable);
free(testVariable);
close(pipeVariable[1]);
close(pipeVariable[0]);
}
return 0;
}
