pointerarray

//用指针数组和快速排序实现文本行的排序
#include <iostream>
using namespace std;
#define MAXLINES 5000
#define MAXLEN 10
#include <string.h>
int readlines(char *linestr[],int nlines);//读入文本行
void writelines(char *linestr[],int nlines);//输出文本行void quicksort(char *linestr[],int left,int right);//文本行排序int getlines1(char a[],int limit)//读入一行数据
{
char c;
for(int i=0;i<limit-1&&(c=getchar())!=EOF&&c!='\n';i++) a[i]=c;
if(c=='\n')
{
a[i]=c;
i++;
}
a[i]='\0';
return i;
}
int readlines(char *linestr[],int nlines)
{
char a[MAXLEN];
char *p;
int len;
int line=0;
while((len=getlines1(a,MAXLEN))>0)
{
if(line>nlines||(p=(char *)malloc(len))==NULL)
return -1;
else
{
strcpy(p,a);
linestr[line]=p;
line++;
}
}
return line;
}
void writelines(char *linestr[],int nlines)
{
for(int i=0;i<nlines;i++)
{
cout<<linestr[i]<<endl;
}
}
int partition(char *linestr[],int left,int right)//快速排序的划分{
char *privokey=linestr[left];
while(left<right)
{
while(left<right&&strcmp(linestr[right],privokey)>0)
right--;
linestr[left]=linestr[right];
while(left<right&&strcmp(linestr[left],privokey)<0)
left++;
linestr[right]=linestr[left];
}
linestr[right]=privokey;
return left;
}
void quicksort(char *linestr[],int left,int right)//快速排序
{
int i;
if(left<right)
{
i=partition(linestr,left,right);
quicksort(linestr, left, i-1);
quicksort(linestr, i+1, right);
}
}
int main()
{
char *linestr[MAXLINES];
int nlines;
nlines=readlines(linestr,MAXLINES);
writelines(linestr, nlines);
quicksort(linestr,0,nlines-1); writelines(linestr, nlines);
return 0;
}。