Objective-C 从函数返回数组

Objective-C 编程语言不允许将整个数组作为参数返回给函数。但是，您可以通过指定不带索引的数组名称来返回指向数组的指针。您将在下一章学习指针，因此可以跳过本章，直到您理解 Objective-C 中指针的概念。

如果要从函数返回一维数组，则必须声明一个返回指针的函数，如下例所示:

int * myFunction() {
.
.
.
}

要记住的第二点是 Objective-C 不主张将局部变量的地址返回到函数外部，因此必须将局部变量定义为 static 静态变量。

现在，考虑下面的函数，它将生成 10 个随机数，并使用数组返回它们，然后按如下方式调用此函数:

#import <Foundation/Foundation.h>
@interface SampleClass:NSObject
- (int *) getRandom;
@end
@implementation SampleClass
/* function to generate and return random numbers */
- (int *) getRandom {
  static int r[10];
  int i;
  /* set the seed */
  srand( (unsigned)time( NULL ) );
  for ( i = 0; i < 10; ++i) {
   r[i] = rand();
   NSLog( @"r[%d] = %d\n", i, r[i]);
  }
  return r;
}
@end
/* main function to call above defined function */
int main () {
  /* a pointer to an int */
  int *p;
  int i;
  SampleClass *sampleClass = [[SampleClass alloc]init];
  p = [sampleClass getRandom];
  for ( i = 0; i < 10; i++ ) {
   NSLog( @"*(p + %d) : %d\n", i, *(p + i));
  }
  return 0;
}

运行一下

结果如下:

2022-07-07 03:22:46.042 demo[5174] r[0] = 1484144440
2022-07-07 03:22:46.043 demo[5174] r[1] = 1477977650
2022-07-07 03:22:46.043 demo[5174] r[2] = 582339137
2022-07-07 03:22:46.043 demo[5174] r[3] = 1949162477
2022-07-07 03:22:46.043 demo[5174] r[4] = 182130657
2022-07-07 03:22:46.043 demo[5174] r[5] = 1969764839
2022-07-07 03:22:46.043 demo[5174] r[6] = 105257148
2022-07-07 03:22:46.043 demo[5174] r[7] = 2047958726
2022-07-07 03:22:46.043 demo[5174] r[8] = 1728142015
2022-07-07 03:22:46.043 demo[5174] r[9] = 1802605257
2022-07-07 03:22:46.043 demo[5174] *(p + 0) : 1484144440
2022-07-07 03:22:46.043 demo[5174] *(p + 1) : 1477977650
2022-07-07 03:22:46.043 demo[5174] *(p + 2) : 582339137
2022-07-07 03:22:46.043 demo[5174] *(p + 3) : 1949162477
2022-07-07 03:22:46.043 demo[5174] *(p + 4) : 182130657
2022-07-07 03:22:46.043 demo[5174] *(p + 5) : 1969764839
2022-07-07 03:22:46.043 demo[5174] *(p + 6) : 105257148
2022-07-07 03:22:46.043 demo[5174] *(p + 7) : 2047958726
2022-07-07 03:22:46.043 demo[5174] *(p + 8) : 1728142015
2022-07-07 03:22:46.043 demo[5174] *(p + 9) : 1802605257

Objective-C 从函数返回数组

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