Question

我是C的新手并试图编写一个程序来对char数组进行排序，方法是通过缩短指向它们的指针数组（一个程序，如D＆amp; K C编程语言pg-108）。这是我的代码 -

#include <stdio.h>
#include <string.h>
#define MAXLINES 5000
#define MAXLEN 100
char *line[MAXLINES];
int readlines(char *line[], int t);
void writelines(char *line[], int t);
void qsort(char *line[], int lo, int m);
int getline(char *, int);
char *alloc(int);
int partition(char *line[], int lo, int m);
int main()
{
    int nlines;   //no of input lines
    if(nlines=readlines(line,MAXLINES)>=0)
    {

        qsort(line, 0, nlines-1);
        writelines(line, nlines);
        return 0;
    }
    else
    {
        printf("Error too many ");
        return 1;

    }



}
char store[10000];   //storage for alloc function
char *p = store;
char *alloc(int n)   //next free position for allocating to the input lines 
{
    if (p + n <= store + 10000)
    {
        p += n;
        return p - n;
    }
    else
        return NULL;
}
int readlines(char *le[], int maxlines) //read the input lines to be sorted
{
    char *p;
    int i = 0;
    char line[MAXLEN];
    int len;
    while ((len=getline(line,MAXLEN)) > 0)
    {
        if ((i >= maxlines)||((p = alloc(len)) == NULL))
        {
            return -1;
        }
        else
        {
            line[len - 1] = '\0';
            le[i++] = p;
            strcpy(p, line);
        }

    }
    return i;

}
void writelines(char *line[], int t)  /*function to print lines after 
{                                          sorting */
    for (int i = 0; i <= t - 1; i++)
        printf("%s\n",line[i]);

}
int getline(char a[], int t)    //function to read a line
{
    int i = 0;                 //to count no of input char  
    int c;
    while ((--t > 0) && (c = getchar()) != '\n'&&c != EOF)
        a[i++] = c;
        ;
    if (c== '\n')
        a[i++]='\n';
    a[i] = '\0';
    return i;

}

void qsort(char *line[], int lo, int m) /*function to quick sort the pointer
{                                         array*/
    if (lo >= m)
        return;
    int p = partition(line,lo,m);
    qsort(line,p+1,m);
    qsort(line,lo,p-1);


}
int partition(char *line[], int lo, int m)   /*function for partition in 
{                                               quick sort */
    int index=0;
    char *t = line[m];
    for (int i = lo; i <= m - 1; i++)
    {
        if (strcmp(line[i], t) <= 0)
        {
            char *p = line[i];
            line[i] = line[index];
            line[index] = p;
            index++;
        }
    }
        char *p = line[m];
        line[m] = line[index];
        line[index] = p;
        return index;
}

它由许多功能组成，我试图对每个功能进行排序描述。即使花了几个小时后我也无法弄清楚为什么它只打印第一个输入线。请帮助弄清楚是什么是这段代码中的问题。

Answer 1

您需要替换：

if(nlines=readlines(line,MAXLINES)>=0)

...与

if((nlines=readlines(line,MAXLINES))>=0)

C程序使用指针数组对char数组进行排序

1 个答案: