Checking Allocation Of malloc/calloc
It seems as a good programing practice to check each time after using malloc/calloc if an address was asagin.
Is there an option to create a function to check if the allocation succeed? as we cast we cast the type of the point each time, so the function will not know which pointer type is it.
For example:
newUser -> name = (char*)malloc(NAME_LENGTH*sizeof(char));
if (newUser -> name == NULL){
printf("Allocation of newUser failedn");
exit(1);
}
User *newUser = (User*)malloc(sizeof(User));
if(newUser == NULL){
printf("Allocation of newUser failedn");
exit(1);
}
Can a function be created that gets newUser and newUser -> name and will exit if allocation failed?
c malloc
asked Dec 27 '18 at 20:05
gbox
3161215
add a comment |
It seems as a good programing practice to check each time after using malloc/calloc if an address was asagin.
Is there an option to create a function to check if the allocation succeed? as we cast we cast the type of the point each time, so the function will not know which pointer type is it.
For example:
newUser -> name = (char*)malloc(NAME_LENGTH*sizeof(char));
if (newUser -> name == NULL){
printf("Allocation of newUser failedn");
exit(1);
}
User *newUser = (User*)malloc(sizeof(User));
if(newUser == NULL){
printf("Allocation of newUser failedn");
exit(1);
}
Can a function be created that gets newUser and newUser -> name and will exit if allocation failed?
c malloc
asked Dec 27 '18 at 20:05
gbox
3161215
1
The cast is unnecessary in C. Your function can simply return avoid *if themallocsucceeded.
– user3386109
Dec 27 '18 at 20:06
add a comment |
It seems as a good programing practice to check each time after using malloc/calloc if an address was asagin.
Is there an option to create a function to check if the allocation succeed? as we cast we cast the type of the point each time, so the function will not know which pointer type is it.
For example:
newUser -> name = (char*)malloc(NAME_LENGTH*sizeof(char));
if (newUser -> name == NULL){
printf("Allocation of newUser failedn");
exit(1);
}
User *newUser = (User*)malloc(sizeof(User));
if(newUser == NULL){
printf("Allocation of newUser failedn");
exit(1);
}
Can a function be created that gets newUser and newUser -> name and will exit if allocation failed?
c malloc
asked Dec 27 '18 at 20:05
gbox
3161215
It seems as a good programing practice to check each time after using malloc/calloc if an address was asagin.
Is there an option to create a function to check if the allocation succeed? as we cast we cast the type of the point each time, so the function will not know which pointer type is it.
For example:
newUser -> name = (char*)malloc(NAME_LENGTH*sizeof(char));
if (newUser -> name == NULL){
printf("Allocation of newUser failedn");
exit(1);
}
User *newUser = (User*)malloc(sizeof(User));
if(newUser == NULL){
printf("Allocation of newUser failedn");
exit(1);
}
Can a function be created that gets newUser and newUser -> name and will exit if allocation failed?
c malloc
c malloc
asked Dec 27 '18 at 20:05
gbox
3161215
asked Dec 27 '18 at 20:05
gbox
3161215
asked Dec 27 '18 at 20:05
gbox
3161215
asked Dec 27 '18 at 20:05
gbox
3161215
asked Dec 27 '18 at 20:05
gbox
3161215
3161215
1
The cast is unnecessary in C. Your function can simply return avoid *if themallocsucceeded.
– user3386109
Dec 27 '18 at 20:06
add a comment |
1
The cast is unnecessary in C. Your function can simply return avoid *if themallocsucceeded.
– user3386109
Dec 27 '18 at 20:06
1
1
The cast is unnecessary in C. Your function can simply return a
void * if the malloc succeeded.– user3386109
Dec 27 '18 at 20:06
The cast is unnecessary in C. Your function can simply return a
void * if the malloc succeeded.– user3386109
Dec 27 '18 at 20:06
add a comment |
1 Answer
1
active
oldest
votes
First, don't cast the return value of malloc as it can hide other errors.
There's no problem wrapping malloc in a function that will do the null check for you. Since malloc takes a size_t and returns a void * your wrapper function should do the same. For example:
void *safe_malloc(size_t s)
{
void *p = malloc(s);
if (!p) {
perror("malloc failed");
exit(1);
}
return p;
}
Then you can use this function anyplace you use malloc without having to explicitly do a NULL check.
answered Dec 27 '18 at 20:08
dbush
93.1k12101134
I personally prefer to replaceperror("malloc failed"); exit(1);withfprintf(stderr, "malloc(%zu) failed: %s.n", s, strerror(errno)); exit(EXIT_FAILURE);as the latter tells me how large an allocation was attempted. I admit: I've created code that failed because I calculatedswrong.. but the more informative error message helped me fix it. (Theexit()bit is irrelevant to that, I just prefer the more informative-to-us-humans form.)
– Nominal Animal
Dec 28 '18 at 3:51
add a comment |
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1 Answer
1
active
oldest
votes
1 Answer
1
active
oldest
votes
active
oldest
votes
active
oldest
votes
First, don't cast the return value of malloc as it can hide other errors.
There's no problem wrapping malloc in a function that will do the null check for you. Since malloc takes a size_t and returns a void * your wrapper function should do the same. For example:
void *safe_malloc(size_t s)
{
void *p = malloc(s);
if (!p) {
perror("malloc failed");
exit(1);
}
return p;
}
Then you can use this function anyplace you use malloc without having to explicitly do a NULL check.
answered Dec 27 '18 at 20:08
dbush
93.1k12101134
I personally prefer to replaceperror("malloc failed"); exit(1);withfprintf(stderr, "malloc(%zu) failed: %s.n", s, strerror(errno)); exit(EXIT_FAILURE);as the latter tells me how large an allocation was attempted. I admit: I've created code that failed because I calculatedswrong.. but the more informative error message helped me fix it. (Theexit()bit is irrelevant to that, I just prefer the more informative-to-us-humans form.)
– Nominal Animal
Dec 28 '18 at 3:51
add a comment |
First, don't cast the return value of malloc as it can hide other errors.
There's no problem wrapping malloc in a function that will do the null check for you. Since malloc takes a size_t and returns a void * your wrapper function should do the same. For example:
void *safe_malloc(size_t s)
{
void *p = malloc(s);
if (!p) {
perror("malloc failed");
exit(1);
}
return p;
}
Then you can use this function anyplace you use malloc without having to explicitly do a NULL check.
answered Dec 27 '18 at 20:08
dbush
93.1k12101134
I personally prefer to replaceperror("malloc failed"); exit(1);withfprintf(stderr, "malloc(%zu) failed: %s.n", s, strerror(errno)); exit(EXIT_FAILURE);as the latter tells me how large an allocation was attempted. I admit: I've created code that failed because I calculatedswrong.. but the more informative error message helped me fix it. (Theexit()bit is irrelevant to that, I just prefer the more informative-to-us-humans form.)
– Nominal Animal
Dec 28 '18 at 3:51
add a comment |
First, don't cast the return value of malloc as it can hide other errors.
There's no problem wrapping malloc in a function that will do the null check for you. Since malloc takes a size_t and returns a void * your wrapper function should do the same. For example:
void *safe_malloc(size_t s)
{
void *p = malloc(s);
if (!p) {
perror("malloc failed");
exit(1);
}
return p;
}
Then you can use this function anyplace you use malloc without having to explicitly do a NULL check.
answered Dec 27 '18 at 20:08
dbush
93.1k12101134
First, don't cast the return value of malloc as it can hide other errors.
There's no problem wrapping malloc in a function that will do the null check for you. Since malloc takes a size_t and returns a void * your wrapper function should do the same. For example:
void *safe_malloc(size_t s)
{
void *p = malloc(s);
if (!p) {
perror("malloc failed");
exit(1);
}
return p;
}
Then you can use this function anyplace you use malloc without having to explicitly do a NULL check.
answered Dec 27 '18 at 20:08
dbush
93.1k12101134
answered Dec 27 '18 at 20:08
dbush
93.1k12101134
answered Dec 27 '18 at 20:08
dbush
93.1k12101134
answered Dec 27 '18 at 20:08
dbush
93.1k12101134
93.1k12101134
I personally prefer to replaceperror("malloc failed"); exit(1);withfprintf(stderr, "malloc(%zu) failed: %s.n", s, strerror(errno)); exit(EXIT_FAILURE);as the latter tells me how large an allocation was attempted. I admit: I've created code that failed because I calculatedswrong.. but the more informative error message helped me fix it. (Theexit()bit is irrelevant to that, I just prefer the more informative-to-us-humans form.)
– Nominal Animal
Dec 28 '18 at 3:51
add a comment |
I personally prefer to replaceperror("malloc failed"); exit(1);withfprintf(stderr, "malloc(%zu) failed: %s.n", s, strerror(errno)); exit(EXIT_FAILURE);as the latter tells me how large an allocation was attempted. I admit: I've created code that failed because I calculatedswrong.. but the more informative error message helped me fix it. (Theexit()bit is irrelevant to that, I just prefer the more informative-to-us-humans form.)
– Nominal Animal
Dec 28 '18 at 3:51
I personally prefer to replace
perror("malloc failed"); exit(1); with fprintf(stderr, "malloc(%zu) failed: %s.n", s, strerror(errno)); exit(EXIT_FAILURE); as the latter tells me how large an allocation was attempted. I admit: I've created code that failed because I calculated s wrong.. but the more informative error message helped me fix it. (The exit() bit is irrelevant to that, I just prefer the more informative-to-us-humans form.)– Nominal Animal
Dec 28 '18 at 3:51
I personally prefer to replace
perror("malloc failed"); exit(1); with fprintf(stderr, "malloc(%zu) failed: %s.n", s, strerror(errno)); exit(EXIT_FAILURE); as the latter tells me how large an allocation was attempted. I admit: I've created code that failed because I calculated s wrong.. but the more informative error message helped me fix it. (The exit() bit is irrelevant to that, I just prefer the more informative-to-us-humans form.)– Nominal Animal
Dec 28 '18 at 3:51
add a comment |
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1
The cast is unnecessary in C. Your function can simply return a
void *if themallocsucceeded.– user3386109
Dec 27 '18 at 20:06