C++ compile error messages - c++

Question

So I have this code that I have to edit a bit but the code itself doesn't compile when I try in mobaxterm and since I don't really have much experience with C++ I hope u guys can help. This is the code:
//critical_example2.c
#include <sys/ipc.h>
#include <sys/sem.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "se207_sems.h"
int main(int argc, char argv[]){
//Use our source file as the "key"
int id=se207_semget("critical_example2.c",1);
int pid=fork();
if(pid){
//P1
while(1){
se207_wait(id);
printf("In critical section P1 ... \n");
rsleep();
printf("Ending critical section P1 ... \n");
se207_signal(id);
}
}else{
//P2
while(1){
se207_wait(id);
printf("In critical section P2 ... \n");
rsleep();
printf("Ending critical section P2 ... \n");
se207_signal(id);
}
}
}
This are the errors i get:
toneve#hvs-its-lnx01:~$ gcc critical_example2.c
In file included from critical_example2.c:9:0:
se207_sems.h: In function ‘se207_wait’:
se207_sems.h:91:6: warning: type of ‘id’ defaults to ‘int’ [-Wimplicit-int]
void se207_wait(id){
^
se207_sems.h: In function ‘se207_signal’:
se207_sems.h:95:6: warning: type of ‘id’ defaults to ‘int’ [-Wimplicit-int]
void se207_signal(id){
This might be the problematic code:
#include <sys/ipc.h>
#include <sys/sem.h>
#include <stdio.h>
#include <stdlib.h>
void rsleep(){
//Random sleep function. Comes in handy demoing stuff.
int stime=2+(rand()/(float)(RAND_MAX))*4;
printf("Sleeping for %d secs\n",stime);
sleep(stime);
}
int se207_semget(char* path, int val){
//Very simple semaphore "getting",
//always uses 1 as the project ID
//takes path to file and initial value of semaphore
int id; /* Number by which the semaphore
is known within a program */
union semun {
int val;
struct semid_ds *buf;
ushort * array;
} argument;
argument.val = val;
/* Create the semaphore with external key from
ftok if it doesn't already
exist. Give permissions to the world. */
id = semget(ftok(path,1), 1, 0666 | IPC_CREAT);
/* Always check system returns. */
if(id < 0)
{
fprintf(stderr, "Unable to obtain semaphore.\n");
exit(0);
}
/* Set the value of the number 0 semaphore in semaphore array # id
to the value "val". */
if( semctl(id, 0, SETVAL, argument) < 0)
fprintf( stderr, "Cannot set semaphore value.\n");
else
fprintf(stderr, "Semaphore %d initialized with path '%s'.\n",
ftok(path,1),path);
return id;
}
void se207_semop(int id,int val){
struct sembuf operations[1];
int retval; /* Return value from semop() */
//simple wait on semaphore
operations[0].sem_num = 0;
/* Which operation? Subtract 1 from semaphore value to wait, add to
signal */
operations[0].sem_op = val;
operations[0].sem_flg = 0;
retval = semop(id, operations, 1);
}
int void se207_wait(id){
se207_semop(id,-1);
}
int void se207_signal(id){
se207_semop(id,1);
}

Answer 1

Remove the int from your se207_wait and se207_signal functions, and declare id as an int in the parameter list.
void se207_wait(int id){
se207_semop(id,-1);
}
void se207_signal(int id){
se207_semop(id,1);
}