C - ポインタ配列: ポインタへのポインタ (一連のテキスト行をソート)

プログラミング言語C 第2版 ANSI規格準拠
B.W. カーニハン D.M. リッチー (著)
石田 晴久 (翻訳)

開発環境

• OS X Lion - Apple(OS)
• Emacs、BBEdit - Bare Bones Software, Inc. (Text Editor)
• プログラミング言語: C
• Clang (コンパイラ)

プログラミング言語C 第2版 ANSI規格準拠 (B.W. カーニハン D.M. リッチー (著)、 石田 晴久 (翻訳)、共立出版)の第5章(ポインタと配列)、5.6(ポインタ配列: ポインタへのポインタ)、演習5-7を解いてみる。

その他参考書籍

• プログラミング言語Cアンサー・ブック 第2版 (クロビス・L．トンド、スコット・E．ギンペル(著)、矢吹 道郎(翻訳))

演習 5-7.

コード

sample.c

#include <stdio.h>
#include <string.h>

#define MAXLINES 5000

char *lineptr[MAXLINES];

int readlines(char *lineptr[], int, char *);
void writelines(char *lineptr[], int);

void qsort(char *lineptr[], int, int);

int main()
{
    int nlines;
    char linestor[MAXLINES];
    if ((nlines = readlines(lineptr, MAXLINES, linestor)) >= 0) {
        qsort(lineptr, 0, nlines - 1);
        writelines(lineptr, nlines);
        return 0;
    } else {
        printf("error: input too big to sort\n");
        return 1;
    }
}

#define MAXLEN 1000
#define MAXSTOR 10000
int my_getline(char *, int);

int readlines(char *lineptr[], int maxlines, char *linestor)
{
    int len, nlines;
    char line[MAXLEN];
    char *p = linestor;
    char *linestop = linestor + MAXSTOR;
    
    nlines = 0;
    while ((len = my_getline(line, MAXLEN)) > 0) {
        if (nlines >= maxlines || p + len > linestop) {
            return -1;
        } else {
            line[len - 1] = '\0';
            strcpy(p, line);
            lineptr[nlines++] = p;
            p += len;
        }
    }
    return nlines;
}

void writelines(char *lineptr[], int nlines)
{
    while (nlines-- > 0) {
        printf("%s\n", *lineptr++);
    }
}

void qsort(char *v[], int left, int right)
{
    int i, last;
    void swap(char *v[], int i, int j);
    
    if (left >= right) {
        return;
    }
    swap(v, left, (left + right) / 2);
    last = left;
    for (i = left + 1; i <= right; i++) {
        if (strcmp(v[i], v[left]) < 0) {
            swap(v, ++last, i);
        }
    }
    swap(v, left, last);
    qsort(v, left, last - 1);
    qsort(v, last + 1, right);
}

void swap(char *v[], int i, int j)
{
    char *temp;
    
    temp = v[i];
    v[i] = v[j];
    v[j] = temp;
}

int my_getline(char *s, int lim)
{
    int c;
    char *t;
    
    t = s;
    while (--lim > 0 && (c = getchar()) != EOF && c != '\n') {
        *s++ = c;
    }
    if (c == '\n') {
        *s++ = c;
    }
    *s = '\0';
    return s - t;
}

入出力結果(Terminal)

$ ./a.out < sample.txt
!@#$%Ah Love! could you and I with Fate conspire
!@#$%Re-mould it nearer to the Heart's Desire!
!@#$%To grasp this sorry Scheme of Things entire,
!@#$%Would not we shatter it to bits -- and then
!@#$%ah love! could you and i with fate conspire
!@#$%re-mould it nearer to the heart's desire!
!@#$%to grasp this sorry scheme of things entire,
!@#$%would not we shatter it to bits -- and then
Ah Love! could you and I with Fate conspire
Re-mould it nearer to the Heart's Desire!
To grasp this sorry Scheme of Things entire,
Would not we shatter it to bits -- and then
ah love! could you and i with fate conspire
re-mould it nearer to the heart's desire!
to grasp this sorry scheme of things entire,
would not we shatter it to bits -- and then
$ cat sample.txt
Ah Love! could you and I with Fate conspire
To grasp this sorry Scheme of Things entire,
Would not we shatter it to bits -- and then
Re-mould it nearer to the Heart's Desire!
ah love! could you and i with fate conspire
to grasp this sorry scheme of things entire,
would not we shatter it to bits -- and then
re-mould it nearer to the heart's desire!
!@#$%Ah Love! could you and I with Fate conspire
!@#$%To grasp this sorry Scheme of Things entire,
!@#$%Would not we shatter it to bits -- and then
!@#$%Re-mould it nearer to the Heart's Desire!
!@#$%ah love! could you and i with fate conspire
!@#$%to grasp this sorry scheme of things entire,
!@#$%would not we shatter it to bits -- and then
!@#$%re-mould it nearer to the heart's desire!
$ ./a.out < sample.c











    
    
    
    
            line[len - 1] = '\0';
            lineptr[nlines++] = p;
            p += len;
            return -1;
            strcpy(p, line);
            swap(v, ++last, i);
        *s++ = c;
        *s++ = c;
        if (nlines >= maxlines || p + len > linestop) {
        if (strcmp(v[i], v[left]) < 0) {
        printf("%s\n", *lineptr++);
        printf("error: input too big to sort\n");
        qsort(lineptr, 0, nlines - 1);
        return 0;
        return 1;
        return;
        writelines(lineptr, nlines);
        }
        }
        } else {
    *s = '\0';
    char *linestop = linestor + MAXSTOR;
    char *p = linestor;
    char *t;
    char *temp;
    char line[MAXLEN];
    char linestor[MAXLINES];
    for (i = left + 1; i <= right; i++) {
    if ((nlines = readlines(lineptr, MAXLINES, linestor)) >= 0) {
    if (c == '\n') {
    if (left >= right) {
    int c;
    int i, last;
    int len, nlines;
    int nlines;
    last = left;
    nlines = 0;
    qsort(v, last + 1, right);
    qsort(v, left, last - 1);
    return nlines;
    return s - t;
    swap(v, left, (left + right) / 2);
    swap(v, left, last);
    t = s;
    temp = v[i];
    v[i] = v[j];
    v[j] = temp;
    void swap(char *v[], int i, int j);
    while ((len = my_getline(line, MAXLEN)) > 0) {
    while (--lim > 0 && (c = getchar()) != EOF && c != '\n') {
    while (nlines-- > 0) {
    }
    }
    }
    }
    }
    }
    }
    } else {
#define MAXLEN 1000
#define MAXLINES 5000
#define MAXSTOR 10000
#include <stdio.h>
#include <string.h>
char *lineptr[MAXLINES];
int main()
int my_getline(char *, int);
int my_getline(char *s, int lim)
int readlines(char *lineptr[], int maxlines, char *linestor)
int readlines(char *lineptr[], int, char *);
void qsort(char *lineptr[], int, int);
void qsort(char *v[], int left, int right)
void swap(char *v[], int i, int j)
void writelines(char *lineptr[], int nlines)
void writelines(char *lineptr[], int);
{
{
{
{
{
{
}
}
}
}
}
}
$