Question

我正在尝试将数组传递给generate函数并在函数中使用其元素。由于某种原因，它只是不断给我函数原型和定义的语法错误。关于我做出改变的地方以及面临麻烦的评论的代码。我试图调试它但不是很成功。错误在第38,81,163行。这是代码：

#include <string.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include "eprintf.h"

enum {
    NPREF   = 2,    /* number of prefix words */
    NHASH   = 4093, /* size of state hash table array */
    MAXGEN  = 10000 /* maximum words generated */
};

typedef struct State State;
typedef struct Suffix Suffix;

struct State {  /* prefix + suffix list */
    char    *pref[NPREF];   /* prefix words */
    Suffix  *suf;           /* list of suffixes */
    State   *next;          /* next in hash table */
};

struct Suffix { /* list of suffixes */
    char    *word;          /* suffix */
    Suffix  *next;          /* next in list of suffixes */
};

State   *lookup(char *prefix[], int create);
void    build(char *prefix[], FILE* myfile); //passing the input stream
void    generate(int nwords, int[] random_num, FILE* oufile); // passing the array and the output stream
void    add(char *prefix[], char *word);

State   *statetab[NHASH];   /* hash table of states */

char NONWORD[] = "\n";  /* cannot appear as real word */

//FILE* random_reader;
//FILE* myfile;


/* markov main: markov-chain random text generation */
int main(void)
{
    int i, nwords = MAXGEN;
    char *prefix[NPREF];        /* current input prefix */

    FILE* random_reader;
    FILE* myfile;
    FILE* outfile;

    int c;
    int element;
    int random_num[10000];
    char* line;
    int j=0;
    random_reader = fopen("../random_num.txt","r");
    myfile = fopen("../alice30.txt","r");
    outfile = fopen("../output/markov_c_out.txt","w");
    while(fgets(line,20,random_reader)!=NULL)
    {
        sscanf(line,"%o",&element);
        random_num[j]= element;
        j++;
    }

    setprogname("markov");


    for (i = 0; i < NPREF; i++) /* set up initial prefix */
        prefix[i] = NONWORD;
    build(prefix, myfile);
    add(prefix, NONWORD);
    generate(nwords, random_num, outfile); // calling the updated function
    return 0;
}   

const int MULTIPLIER = 31;  /* for hash() */

/* hash: compute hash value for array of NPREF strings */

unsigned int hash(char *s[NPREF])
{
    unsigned int h;
    unsigned char *p;
    int i;

    h = 0;
    for (i = 0; i < NPREF; i++)
        for (p = (unsigned char *) s[i]; *p != '\0'; p++)
            h = MULTIPLIER * h + *p;
    return h % NHASH;
}

/* lookup: search for prefix; create if requested. */
/*  returns pointer if present or created; NULL if not. */
/*  creation doesn't strdup so strings mustn't change later. */

State* lookup(char *prefix[NPREF], int create)
{
    int i, h;
    State *sp;

    h = hash(prefix);
    for (sp = statetab[h]; sp != NULL; sp = sp->next) {
        for (i = 0; i < NPREF; i++)
            if (strcmp(prefix[i], sp->pref[i]) != 0)
                break;
        if (i == NPREF)     /* found it */
            return sp;
    }
    if (create) {
        sp = (State *) emalloc(sizeof(State));
        for (i = 0; i < NPREF; i++)
            sp->pref[i] = prefix[i];
        sp->suf = NULL;
        sp->next = statetab[h];
        statetab[h] = sp;
    }
    return sp;
}

/* addsuffix: add to state. suffix must not change later */

void addsuffix(State *sp, char *suffix)
{
    Suffix *suf;

    suf = (Suffix *) emalloc(sizeof(Suffix));
    suf->word = suffix;
    suf->next = sp->suf;
    sp->suf = suf;
}

/* add: add word to suffix list, update prefix */

void add(char *prefix[NPREF], char *suffix)
{
    State *sp;

    sp = lookup(prefix, 1);  /* create if not found */
    addsuffix(sp, suffix);
    /* move the words down the prefix */
    memmove(prefix, prefix+1, (NPREF-1)*sizeof(prefix[0]));
    prefix[NPREF-1] = suffix;
}

/* build: read input, build prefix table */
void build(char *prefix[NPREF], FILE *myfile)
{
    char buf[100], fmt[10];

    /* create a format string; %s could overflow buf */
    sprintf(fmt, "%%%ds", sizeof(buf)-1);
    while (fscanf(myfile, fmt, buf) != EOF)
        add(prefix, estrdup(buf));
}

/* generate: produce output, one word per line */

void generate(int nwords, int[] random_num, FILE* oufile)
{
    State *sp;
    Suffix *suf;
    char *prefix[NPREF], *w;
    int i, nmatch;

    for (i = 0; i < NPREF; i++) /* reset initial prefix */
        prefix[i] = NONWORD;

    for (i = 0; i < nwords; i++) {
        sp = lookup(prefix, 0);
        if (sp == NULL)
            eprintf("internal error: lookup failed");
        nmatch = 0;
        for (suf = sp->suf; suf != NULL; suf = suf->next)
            if (random_num[i] % ++nmatch == 0) //using the elements of the array
                w = suf->word;
        if (nmatch == 0)
            eprintf("internal error: no suffix %d %s", i, prefix[0]);
        if (strcmp(w, NONWORD) == 0)
            break;

        fprintf(outfile, w);
        memmove(prefix, prefix+1, (NPREF-1)*sizeof(prefix[0]));
        prefix[NPREF-1] = w;
    }
}

Answer 1

generate的原型应该是

void generate(int nwords, int random_num[], FILE* oufile);

在声明和定义中。 int[] foo无效的C语法。

另一个错误是因为您忘记声明estrdup。如果没有声明，C假定其原型的返回值为int，因此错误

a.c:136: note: expected ‘char *’ but argument is of type ‘int’

很高兴看到有人正在阅读编程实践，这是我的最爱之一：）

传递数组和读/写文件

1 个答案: