实验五

/*二分法查找*/ 
#include<stdio.h>
#define N 5
int brainsearch(int *x,int n ,int item );
int main()
{
	int a[N]={1,3,9,16,21};
	int i,index,key;
	printf("数组a中的数据：\n");
	for(i=0;i<N;i++)
	  printf("%d ",a[i]);
	printf("\n");
	printf("待查找的数据：\n");
	  scanf("%d",&key);
	index=brainsearch(a,N,key);
	if(index>=0)
	  printf("%d在数组中,下标为%d\n",key,index);
	else
	  printf("%d不在数组中\n",key);
	return 0;
}
int brainsearch(int *x,int n,int item)
{
	int *p,low=0,high=n-1,mid;
	p=x;
	while(low<=high)
	{
		mid=(high+low)/2;
		if(*(p+mid)==item)
		  return mid;
		else if(*(p+mid)<item)
		  low=mid+1;
		else if(*(p+mid)>item)
		  high=mid-1;
	
	}
	return -1;
}

#include<stdio.h>
#include<string.h> 
void selectsort(char str[][20],int n);
int main()
{
	char name[][20]={"John","Alex","Joseph","Candy","Geoge"};
	int i;
	printf("输出初始名单：\n");
	for(i=0;i<5;i++)
	  printf("%s\n",name[i]);
	selectsort(name,5);
	printf("按字典序输出名单：\n");
	for(i=0;i<5;i++)
	  printf("%s\n",name[i]);
	return 0;
}
void selectsort(char str[][20],int n)
{
     int j,i=0;
     char t[100];
     for(i=0;i<n;i++)
	  for(j=i+1;j<=n-1;j++)	
	  	if(strcmp(str[i],str[j])>0)
	      {
	      	strcpy(t,str[i]);
	      	strcpy(str[i],str[j]);
	      	strcpy(str[j],t);
		  }
	} 

/*用指针处理字符,删除前导* */
#include<stdio.h>
void delPrefixStar(char[]);
int main()
{
	char string[80];
	printf("输入一个字符串：\n");
	gets(string);
	printf("\n删除前导*之前的字符串：\n");
	puts(string);
	delPrefixStar(string);
	printf("\n删除前导*后的字符串：\n");
	puts(string);
	return 0;
 } 
void delPrefixStar(char s[])
{
	char *target,*source;
	source=s;
	while(*source==‘*‘)
	source++;
	target=s;
	while(*source)
	{
		*target=*source;
		source++;
		target++;
	}
	*target=‘\0‘;
}

#include<stdio.h>
void delPrefixStar(char[]);
int main()
{
	char string[80];
	printf("输入一个字符串：\n");
	gets(string);
	printf("\n删除中间的和后面的*前的字符串：\n");
	puts(string);
	delPrefixStar(string);
	printf("\n删除中间和后面的*后的字符串：\n");
	puts(string);
	return 0;
 } 
void delPrefixStar(char s[])
{
	char *source,*target;
	source=s;
	while(*source==‘*‘)
	source++;
	target=source;
	while(*source)
	{
		source++;
		if(*source!=‘*‘)
		{
			target++;
			*target=*source;
		}
	}
	

#include<stdio.h>
void delPrefixStar(char[]);
int main()
{
	char string[80];

	printf("输入一个字符串：\n");
	gets(string);

	printf("\n删除中间的*之前的字符串：\n");
	puts(string);
	delPrefixStar(string);
	printf("\n删除中间的*后的字符串：\n");
	puts(string);
	return 0;
 } 
void delPrefixStar(char s[])
{
	char *source,*tail,*target;
	tail=s;
	while(*tail)
	  tail++;
	tail--;
	while(*tail==‘*‘)
	  tail--;
	source=s;
	while(*source==‘*‘)
	  source++;
	target=source;
	while(*source&&source<tail)
	{
		source++;
		if(*source!=‘*‘)
		  {
		  	target++;
		  	*target=*source;
		  }
	}
	while(*source)
	{
		source++;
	   	target++;
	   	*target=*source;
	}
}

/*使用选择法对一组整数由大到小排序*/
#include<stdio.h>
#define N 5
void input(int[],int);
void output(int[],int);
void selectsort(int [],int);
int main()
{
	int a[N];
	printf("输入5个整数：\n");
	input(a,N);
	selectsort(a,N);
	printf("排序后的数据：\n");
	output(a,N); 
	return 0;
 } 
 void input(int x[],int n)
 {
 	int i=0;
 	for(i=0;i<n;i++)
 	scanf("%d,",&x[i]);
 }
 void output(int y[],int f)
 {
 	int i=0;
 	for(i=0;i<f;i++)
 	printf("%d  ",y[i]);
 }
 void selectsort(int z[],int m)
 {
 	int i,t,k,j;
 	for(i=0;i<m-1;i++)
 	{
 		k=i;
 		for(j=i+1;j<=m-i;j++)
 		{
 			if(z[k]>z[j])
 			  k=j;
		 }
		 if(k!=i)
		 {
		 t=z[i];
		 z[i]=z[k];
		 z[k]=t;
	     }
	 }
 	
 }