Error Checking Malloc
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Malloc Check Failed
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Check Malloc Failure
that `malloc` succeeded in C up vote 5 down vote favorite 1 I want to allocate memory using malloc and check that it succeeded. something like: if (!(new_list=(vlist)malloc(sizeof (var_list)))) return -1; how do I check success? c malloc share|improve this question asked Apr 9 '11 at 19:50 Ilya Melamed 3,465174786 Your code already does check success. On failure it returns -1, on realloc error checking success it carries on to the next line. I hope vlist is a typedef for var_list*. –Steve Jessop Apr 9 '11 at 20:10 add a comment| 3 Answers 3 active oldest votes up vote 9 down vote accepted malloc returns a null pointer on failure. So, if what you received isn't null, then it points to a valid block of memory. Since NULL evaluates to false in an if statement, you can check it in a very straightforward manner: value = malloc(...); if(value) { // value isn't null } else { // value is null } share|improve this answer edited Apr 10 '11 at 19:00 answered Apr 9 '11 at 19:51 Etienne de Martel 20.2k26079 Zero can be used wherever NULL is appropriate, but NULL is not zero. It's NULL. It does always evaluate to false, though. –Philip Apr 9 '11 at 23:38 @Phillip My bad, I wrongly assumed that C was like C++ in this regard. –Etienne de Martel Apr 10 '11 at 19:00 2 in C (unlike C++) (void*)0 is a null pointer constant. That's because a void* pointer in C (unlik
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What To Do If Malloc Fails
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Malloc Error C++
Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping malloc errno each other. Join them; it only takes a minute: Sign up How detect malloc failure? up vote 13 down vote favorite 2 What is the portable way to check whether malloc failed to allocate non-zero memory block? c http://stackoverflow.com/questions/5607455/checking-that-malloc-succeeded-in-c share|improve this question edited Jan 24 at 20:26 Ziezi 3,19031228 asked Jun 13 '11 at 1:43 pic11 4,59394988 add a comment| 5 Answers 5 active oldest votes up vote 17 down vote accepted According to the Single Unix Specification, malloc will return NULL and set errno when it fails. share|improve this answer answered Jun 13 '11 at 1:47 a3nm 4,27521428 Thanks for a quick answer. Is errno thread safe? –pic11 Jun 13 '11 at 1:52 http://stackoverflow.com/questions/6325940/how-detect-malloc-failure 6 errno is thread-safe. Do not listen to people who tell you otherwise. –R.. Jun 13 '11 at 1:59 6 The citation is XBD 3.396: pubs.opengroup.org/onlinepubs/9699919799/basedefs/… A single flow of control within a process. Each thread has its own thread ID, scheduling priority and policy, errno value, thread-specific key/value bindings, and the required system resources to support a flow of control. –R.. Jun 13 '11 at 2:03 add a comment| up vote 9 down vote I always do this: tok = malloc( sizeof( char ) * ( strlen(tc) + 1 ) ); if( tok == NULL ) { /* Malloc failed, deal with it */ } Some people do tok = (type) malloc( ... ) but you should cast the result because apparently it covers up some nasty errors. I will do some research and see if I can find out exactly what they are. Edit: Casting malloc can hide a missing #include
here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site About Us Learn more about Stack Overflow the company Business Learn more about hiring developers or posting ads http://stackoverflow.com/questions/26831981/should-i-check-if-malloc-was-successful with us Stack Overflow Questions Jobs Documentation Tags Users Badges Ask Question x Dismiss Join the Stack Overflow Community Stack Overflow is a community of 4.7 million programmers, just like you, helping each other. Join them; it only takes a minute: Sign up Should I check if malloc() was successful? up vote 1 down vote favorite Should one check after each malloc() if it was successful? Is it at all possible that a malloc() fails? What happens then? At school we were error checking told that we should check, ie.: arr = (int) malloc(sizeof(int)*x*y); if(arr==NULL){ printf("Error. Allocation was unsuccessful. \n"); return 1; } What is the practice regarding this? Can I do it this way: if(!(arr = (int) malloc(sizeof(int)*x*y))