C語言增量內存申請 realloc

void* realloc (void* ptr, size_t size); Reallocate memory block

Changes the size of the memory block pointed to by?ptr.
The function may move the memory block to a new location (whose address is returned by the function).

The content of the memory block is preserved up to the lesser of the new and old sizes, even if the block is moved to a new location. If the new?size?is larger, the value of the newly allocated portion is indeterminate.

【如果申請長度小于原來長度，原來內容被截斷；等于則內容不變，如果申請長度大于原來長度，多出部分的內存，其內容是不確定的，原來內容不變】

【但不管哪種情況，內存地址都可能改變，相等情況下可能不變】

In case that?ptr?is a null pointer, the function behaves like?malloc, assigning a new block of?size?bytes and returning a pointer to its beginning.

【如果ptr是空，則此時函數相當于malloc的功能】

?代碼如下：

1 /* realloc example: rememb-o-matic */ 2 #include <stdio.h> /* printf, scanf, puts */ 3 #include <stdlib.h> /* realloc, free, exit, NULL */ 4 5 int main () 6 { 7 int input,n; 8 int count = 0; 9 int* numbers = NULL; 10 int* more_numbers = NULL; 11 12 do { 13 printf ("Enter an integer value (0 to end): "); 14 scanf ("%d", &input); 15 count++; 16 17 more_numbers = (int*) realloc (numbers, count * sizeof(int)); 18 19 if (more_numbers!=NULL) { 20 numbers=more_numbers; 21 numbers[count-1]=input; 22 } 23 else { 24 free (numbers); 25 puts ("Error (re)allocating memory"); 26 exit (1); 27 } 28 } while (input!=0); 29 30 printf ("Numbers entered: "); 31 for (n=0;n<count;n++) printf ("%d ",numbers[n]); 32 free (numbers); 33 34 return 0; View Code

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posted on 2018-02-09 18:01 時空觀察者9號 閱讀(...) 評論(...) 編輯 收藏

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