我最近在C编程方面是全新的，我开始更多地研究指针，我遇到了代码问题。
所以我尝试将字符串传递给结构中的final int periodicity = (int) TimeUnit.HOURS.toSeconds(24);
final int toleranceInterval = (int) TimeUnit.HOURS.toSeconds(1);
FirebaseJobDispatcher dispatcher = new FirebaseJobDispatcher(new GooglePlayDriver(this));
Job job = dispatcher.newJobBuilder()
.setService(UpdateTVJobService.class)
.setTag(JOB_TAG)
.setTrigger(Trigger.executionWindow(periodicity, periodicity + toleranceInterval))
.setLifetime(Lifetime.FOREVER)
.setRecurring(true)
.setReplaceCurrent(true)
.build();
int result = dispatcher.schedule(job);
if (result != FirebaseJobDispatcher.SCHEDULE_RESULT_SUCCESS) {
Log.d("JOB_TAG", "ERROR ON SCHEDULE");
}
，但我总是遇到错误。在此先感谢这里是一些代码
这是我使用的结构。
char**这就是我试图投入的内容。在第一个内部，如果你看到我尝试typedef struct Queue {
int capacity;
int front;
int rear;
int size;
char **car_id;
};
但失败了。即使我把＆amp;或*。
strcpy答案 0 :(得分：3)
使用结构很容易搞乱内存分配和释放。因此，最好始终为每个结构编写new和destroy函数。
/* To avoid confusion, it's best to declare structs as type definitions
and name them Something_t. Capital letter to avoid conflict with
built in types, _t to note that it is a type, and to avoid conflict
with other names. */
typedef struct {
/* Using size_t means less type casting */
size_t capacity;
int front;
int rear;
int size;
char **items;
} Queue_t;
Queue_t *Queue_new( const size_t capacity ) {
/* Use calloc because we have to zero everything anyway */
Queue_t *queue = calloc( 1, sizeof(Queue_t) );
/* Allocate enough space to store a list of whatever
queue->items is a list of */
queue->capacity = capacity;
queue->items = malloc( capacity * sizeof(*(queue->items)) );
return queue;
}
void Queue_destroy( Queue_t *queue ) {
/* Since items were copied into the list, it's the queue's responsibility
to free them */
for( int i = queue->front; i < queue->rear; i++ ) {
free( queue->items[i] );
}
/* Now free the list of items */
free( queue->items );
/* And finally the struct itself */
free( queue );
}
现在已经分配了结构及其项目列表，您必须确保不添加太多项目。添加到队列中的代码永远不会检查它是否超出了队列的容量。出于这个原因，最好编写一个函数来添加能够正确检查容量的项目。
void Queue_add( Queue_t *queue, const char *item ) {
if( queue->size >= (int)queue->capacity ) {
fprintf(stderr, "Queue capacity of %zu exceeded!\n", queue->capacity);
exit(1);
}
/* You used strcpy in your example, so I'm following that.
You could also not copy and store the original pointer. */
queue->items[ queue->rear ] = strdup( item );
/* I don't know if this is right */
queue->rear++;
queue->size++;
}
排队逻辑可能是错误的，我对队列不好，但你明白了。您甚至可以稍后将队列扩展为自动调整大小。
现在，您可以单独测试这些工作。一旦确定它们有效，您就可以尝试从文件中读取并使用队列功能。
int main() {
char filename[] = "car.txt";
FILE *fp = fopen(filename,"r");
if (fp == NULL) {
fprintf(stderr, "Couldn't read '%s': %s\n", filename, strerror(errno));
exit(1);
}
/* Just picked a number out of thin air */
Queue_t *qboats = Queue_new(256);
Queue_t *sboats = Queue_new(256);
char line[10];
while( fgets( line, 10, fp) != NULL ) {
size_t len = strlen(line);
/* Choose the right queue to use */
Queue_t *queue;
switch ( line[len-2] ) {
case 'S':
queue = sboats;
break;
case 'Q':
queue = qboats;
break;
default:
fprintf( stderr, "Can't understand line '%s'\n", line );
continue;
break;
}
/* Chop off the identifier */
line[len - 2] = '\0';
/* Add to the queue */
Queue_add( queue, line );
}
/* Do something with the queues. This should probably be Queue_print(). */
for( int i = qboats->front; i < qboats->rear; i++ ) {
printf("qboat: %s\n", qboats->items[i]);
}
for( int i = sboats->front; i < sboats->rear; i++ ) {
printf("sboat: %s\n", sboats->items[i]);
}
/* Now clean them up */
Queue_destroy( sboats );
Queue_destroy( qboats );
}
现在大部分工作都在确定使用哪个队列。