二分查找

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对于有序数组的查找来说，折半查找时一种性能卓越的算法。本次程序从文件中读取数据并存到文件中

程序为

#include<stdio.h>#include<stdlib.h>int search(int num[],int key,int len);int main(){   FILE * fp;   char * pchBuf;   char  tmp[5];   int Len,key;   int i,j=0,k=0,nLen=0;   int num[200];   fp=fopen("bs-1.txt","r");                    //以只读打开文件   fseek(fp,0,SEEK_END);                        //将文件指针移到结尾   Len=ftell(fp);                               //计算文件长度   rewind(fp);                                  //将文件指针移到开头   pchBuf=(char*)malloc(sizeof(char)*Len+1);    //在堆里开空间存放文件的内容    if(!pchBuf)                                 //如果没有分配退出{    printf("内存不够!\n");exit(0);}    Len = fread(pchBuf,sizeof(char),Len,fp);   //将文件内容放入空间中，并自动调整长度    fclose(fp);                                //关闭文件pchBuf[Len] = '\0';                        //将字符长结尾附零for (i=0;i<=Len;i++)                     {tmp[j++]=*(pchBuf+i);                         //找到字符串开头if (*(pchBuf+i)==',' ||*(pchBuf+i)=='\0' )    //判断是否遇到逗号和结尾{    tmp[j] = '\0';                            //将子字符串附零        nLen++;  num[k++]=atoi(tmp);                        //将字符串转化为整形j=0;                                      //查找下一个字符串}} printf("请输入一个要查找的数"); scanf("%d",&key);        i=search(num,key,nLen);printf("数的下标是%d",i);   return 0;}//二分算法int search(int num[],int key,int len){    int n;                //用于返回的数组下标int begin=0;          //开始位置int end=len-1;        //结尾位置while(begin<=end){    n=(begin+end)/2;if(num[n]==key){    return n;}else if(key<num[n]){    end=n-1;}else{    begin=n+1;}}return  0;}

文件为bx-1.txt

1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,25,27,28,29,30,31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58,59,60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94,95,96,97,98,99,100,101,102,103,104,105,106,107,108,109,110,111,112,113,114,115,116,117,118,119,120,121,122,123,124,125,126,127,128,129,130,131,132,133,134,135,136,137,138,139,140,141,142,143,144,145,146,147,148,149,150

本次只是简单二分查找，并从文件中读取，大家看一下，有不对之处，请指出

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