C doesn’t have a foreach, but macros are frequently used to emulate that:
#define for_each_item(item, list)
for(T * item = list->head; item != NULL; item = item->next)
And can be used like
for_each_item(i, processes) {
i->wakeup();
}
Iteration over an array is also possible:
#define foreach(item, array)
for(int keep = 1,
count = 0,
size = sizeof (array) / sizeof *(array);
keep && count != size;
keep = !keep, count++)
for(item = (array) + count; keep; keep = !keep)
And can be used like
int values[] = { 1, 2, 3 };
foreach(int *v, values) {
printf(“value: %dn”, *v);
}
Edit: In case you are also interested in C++ solutions, C++ has a native for-each syntax called “range based for”
Here is a full program example of a for-each macro in C99:
#include
typedef struct list_node list_node;
struct list_node {
list_node *next;
void *data;
};
#define FOR_EACH(item, list)
for (list_node *(item) = (list); (item); (item) = (item)->next)
int
main(int argc, char *argv[])
{
list_node list[] = {
{ .next = &list[1], .data = “test 1” },
{ .next = &list[2], .data = “test 2” },
{ .next = NULL, .data = “test 3” }
};
FOR_EACH(item, list)
puts((char *) item->data);
return 0;
}