在相邻元素相差1的数组中查找某一特定元素第一次出现的位置

#include <stdio.h>
#include <stdlib.h>

int main(void)
{
int a[] = {3,4,3,2,1,2,3,4,3,4,5,6,5};
int i, next, to_search;
int len = sizeof(a);
int count = 0, found = 0;

printf("Please input the number that you want to search: ");
scanf("%d",&to_search);

for( i=0; i<len; i+=next)
{
++count;
if( a[i] == to_search )
{
found = 1;
break;
}
else
next = abs(a[i]-to_search);
}
printf("Search times: %d\n",count);
if( found )
printf("%d is at a[%d]\n",to_search, i);
else
printf("Not found.\n");

return 0;
}