输入确定数组长度

用 malloc库函数实现

/* malloc example: random string generator*/

#include <stdio.h>      /* printf, scanf, NULL */

#include <stdlib.h>     /* malloc, free, rand */

int main ()

{

  int i,n;

  char * buffer;

  printf ("How long do you want the string? ");

  scanf ("%d", &i);

  buffer = (char*) malloc (i+1);

  if (buffer==NULL) exit (1);

  for (n=0; n<i; n++)

    buffer[n]=rand()%26+'a';

  buffer[i]='\0';

  printf ("Random string: %s\n",buffer);

  free (buffer);

  return 0;

}