Tri d'un fichier texte

Question

/* Program that reads a sequence of words from keyboard 
    and prints the list of words without duplicates and 
    sorted in ascending lexicographic order. 
    The input words are written one per line and the 
    sequence is terminated by an empty line. 
    The program works with at most MAX words, each at 
    most MAXL characters long. Longer words are truncated 
    and words in excess are ignored. 
*/ 

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

#define MAXL   80 /* maximum word length */ 
#define MAX   100 /* maximum number of words */ 

/* word storage */ 
char storage[MAX][MAXL]; 
char *words[MAX]; 

void init(char *pnt[], char matr[][MAXL], int max); 
int read_words (char *s[], int max); 
void sort_strings (char *s[], int len); 
void swap_char_pnt(char **xp, char **yp); 
void print_words(char *s[], int n); 
int find (char *s[], char w[], int n); 

main() 
{ 
    int nw; /* actual number of words */ 

    /* initialize array of pointers */ 
    init(words, storage, MAX); 

    /* read and store words */ 
    printf("Enter words one per line\n"); 
    nw = read_words(words, MAX); 

    printf("\nList of unsorted words:\n"); 
    print_words(words, nw); 

    /* sort words */ 
    sort_strings(words, nw); 

    /* print words */ 
    printf("\nList of sorted words:\n"); 
    print_words(words, nw); 
} 


/* initializes an array of pointers to the rows of 
a matrix of characters 
max is the number of pointers to initialize 
*/ 
void init(char *pnt[], char matr[][MAXL], int max) { 
    int i; 

    for (i=0; i<max; i++) 
    pnt[i] = matr[i]; 
} 

/* Reads a sequence of words from stdin, one per line 
Reads at most max words and stores them in s 
Returns actual number of words read 
*/ 
int read_words (char *s[], int max) 
{ 
    int i; 
    fgets(s[0], MAXL, stdin); 
    for (i=1; i<max && fgets(s[i], MAXL, stdin)!=NULL;) { 
     if(!strcmp(s[i],"\n")) 
    break; 
    if (find(s, s[i], i)==-1) 
    i++; 
    } 
    return i; 
} 

int find (char *s[], char w[], int n) 
{ 
    int i; 

    if (n<0) 
    return -1; 
    for (i=0; i<n; i++) 
    if (!strcmp(s[i],w)) 
    break; 
    if (i==n) 
    return -1; 
    else 
    return i; 
} 

/* Sorts an aray of pointers to strings in ascending order 
*/ 
void sort_strings (char *s[], int len) 
{ 
    int i,k; /* vector index and counter */ 
    char swaps=1; /* boolean variable: true if any swap has occurred in last round */ 

    for (k=1; k<=len-1 && swaps; k++) { 
    swaps=0; 
    for (i=0; i<len-k; i++) 
    if (strcmp(s[i],s[i+1])>0) { 
     /* swap */ 
     swap_char_pnt(&s[i], &s[i+1]); 
     swaps=1; 
    } 
    } 
} 

void swap_char_pnt(char **xp, char **yp) { 
    char *temp; 

    temp = *xp; 
    *xp = *yp; 
    *yp = temp; 
} 

void print_words(char *s[], int n) 
{ 
    int i; 

    for (i=0; i<n; i++) 
    printf("%s", s[i]); 

} 

Que puis-je faire pour trier le fichier texte dans l'ordre croissant des chaînes.

Answer 1

• Lire toutes les lignes d'une matrice de char* s,

• définir une fonction de comparaison de chaîne pour qsort de fichier <stdlib.h> d'en-tête:

  int compare(const void* a, const void* b) { 
      return strcmp(*(const char**)a, *(const char**)b); 
  } 
  

• utilisation qsort() sur ce tableau, à l'aide de cette fonction compare .