Using malloc() properly

Question

I use malloc while i was writing code in C, but i am getting

[Warning] conflicting types for built-in function 'malloc'

this warning when i compile.

and this is the code that i use :

starttimer(AorB,increment)
int AorB;  /* A or B is trying to stop timer */
float increment;
{

 struct event *q;
 struct event *evptr;
 char *malloc();

 if (TRACE>2)
    printf("          START TIMER: starting timer at %f\n",time);
 /* be nice: check to see if timer is already started, if so, then  warn */
/* for (q=evlist; q!=NULL && q->next!=NULL; q = q->next)  */
   for (q=evlist; q!=NULL ; q = q->next)  
    if ( (q->evtype==TIMER_INTERRUPT  && q->eventity==AorB) ) { 
      printf("Warning: attempt to start a timer that is already started\n");
      return;
      }

/* create future event for when timer goes off */
   evptr = (struct event *)malloc(sizeof(struct event));
   evptr->evtime =  time + increment;
   evptr->evtype =  TIMER_INTERRUPT;
   evptr->eventity = AorB;
   insertevent(evptr);
}

thanks in advance.

char *malloc(); - what are you doing?

someuser
– someuser

2014-02-27 07:03:40 +00:00
Commented Feb 27, 2014 at 7:03 — someuser
– someuser, Commented Feb 27, 2014 at 7:03

Jonathon Reinhart · Accepted Answer · 2014-02-27 07:09:22Z

5

You need to #include <stdlib.h>, and remove your bogus declaration: char *malloc();

Also, you need to find a newer C reference! The K&R function declaration syntax has been obsolete for a very long time.

Consider changing:

starttimer(AorB,increment)
int AorB;  /* A or B is trying to stop timer */
float increment;
{

to the (sane-looking) ANSI C standard:

int starttimer(int AorB, float increment) {

edited Feb 27, 2014 at 7:09

answered Feb 27, 2014 at 7:03

Jonathon Reinhart

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3 Comments

mustafa Over a year ago

i've already add #include <stdlib.h> but it still gives me same error

Jonathon Reinhart Over a year ago

Remove the char *malloc()

user149341 Over a year ago

To put a finer point on it: K&R function declarations have been obsolete since the release of the ANSI C standard in 1989. This was about 25 years ago. It's frankly amazing that compilers still tolerate it.

Sakthi Kumar · Accepted Answer · 2014-02-27 07:03:51Z

1

char *malloc();

I am not sure why you redeclare the library function malloc. Any how here is the declaration of malloc

void *malloc(size_t size);

Please include <stdlib.h>

answered Feb 27, 2014 at 7:03

Sakthi Kumar

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2 Comments

Lee Duhem Over a year ago

The asker does not redefine malloc(), just declare it with a wrong type.

Sakthi Kumar Over a year ago

@leeduhem thanks for spotting that. updated the answer:)

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