数组排序，查找

#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
int main()
{
  int i, j, t, a[10];
  printf("请输人10个整数:");
  for (j = 0; j < 10; j++) {
  scanf("%d", &a[j]);
  }
  printf("\n");
  for (i = 0; i < 9; i++) {/* 外循环,循环9次*/
    for (j = i + 1; j < 10; j++) {/*内循环 */
    if (a[i] > a[j]) {//如果前面的数比后面的大
      t = a[i]; a[i] = a[j]; a[j] = t;/*交换位置*/
    }
    }
  }
  printf("排序之后:\n");
  for (j = 0; j < 10; j++) {
    printf("%4d",a[j]);
  }
  return 0;
}

#include<stdio.h>
int main() {
  int i, j, t, a[10], k;
  printf("请输人10个整数:");
  for (j = 0; j < 10; j++) {
  scanf("%d", &a[j]);
  }
  printf("\n");
  for (i = 0; i < 9; i++) {/* 外循环,循环9次*/
  k = i;
  for (j = i + 1; j < 10; j++) {
    if (a[k] > a[j]) {
    k = j;//记录最小的数的下标
    }
  }
  if (i != k) {//这里是前面令k = i,如果交换了k就不等于i了 
    t = a[k], a[k] = a[i], a[i] = t;
  }
  }
  printf("排序之后:\n");
  for (j = 0; j < 10; j++) {
  printf("%4d",a[j]);
  }
  return 0;
}

include <stdio.h>
int main()
{
  int arr[] = {1,2,3,4,5,6,7,8,9,10};
  int left = 0;
  int right = sizeof(arr)/sizeof(arr[0])-1;
  int key = 7;//要找的数字
  int mid = 0;//记录中间元素的下标
  int find = 0;
  while(left<=right)
  {
    mid = (left+right)/2;
    if(arr[mid]>key)
    {
    right = mid-1;
    }
    else if(arr[mid] < key)
    {
    left = mid+1;
    }
    else
    {
    find = 1;
    break;
    }
 }
  if(1 == find )
  printf("找到了,下标是%d\n", mid);
  else
  printf("找不到\n");
}