c - 使用 argv[] 从命令行读取文件

Question

我想获取一个输入文件并从中创建索引并将其保存到另一个文件。

当我像这样将输入文件重定向到我的程序时，一切正常

./myprog <text.txt

但是当我尝试使用 argv[1] 从命令行将文件作为参数打开时，它不起作用，我无法理解为什么

我猜这与我打开文件的方式有关

发布整个代码，但我想当我读取文件时问题出在代码顶部

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

#define MAXW 1000
#define MAXC 100



typedef struct {
    char seen[MAXC];

    char lines[1024];


} wfstruct;

int get_word_freq (wfstruct *words, size_t *idx, FILE *fp);
int compare (const void *a, const void *b);

int main (int argc, char **argv) {
printf("%d",argc);
printf("%s",argv[1]);
    /* initialize variables & open file or stdin for seening */
    wfstruct words[MAXW] = {{{ 0 }, 0}};
    size_t i, idx = 0;

FILE *fp2;
if(argc>2)
{
printf("too much args\n");
return 1;
}
if(argc<2)
{
printf("give me a file\n");
return 1;

}

FILE *fp=fopen(argv[1],"r");
get_word_freq (words, &idx, fp);






    /* sort words alphabetically */
    qsort (words, idx, sizeof *words, compare);
   fp2 = fopen("Output.txt", "w");
 fprintf(fp2, "The occurences of words are");
    printf ("\nthe occurrence of words are:\n\n");
    for (i = 0; i < idx; i++)
{
 fprintf(fp2, "  %-28s :  seen in lines %s \n", words[i].seen, words[i].lines);

        printf ("  %-28s :  seen in lines %s \n", words[i].seen, words[i].lines);
}


fclose(fp2);




    return 0;
}

int get_word_freq (wfstruct *words, size_t *idx, FILE *fp)
{

    size_t i;






    /* read each word in file */

   char *word;
    word = malloc(sizeof(char));

int now;
int line = 1;
int j=0;
for (;;j++)
{
    now=getchar();
    if(now==EOF)
    {
        break;
    }
    if(!isalpha(now)){
        word[j] = '\0';
        j=-1;
         for (i = 0; i < *idx; i++) {
            /* if word already 'seen', update 'words[i]. freq' count */
            if (strcmp (words[i].seen, word) == 0) {

          sprintf(words[i].lines + strlen(words[i].lines),"%d,",line);







                goto skipdup;   /* skip adding word to 'words[i].seen' */
            }
        } /* add to 'words[*idx].seen', update words[*idx].freq & '*idx' */
        strcpy (words[*idx].seen, word);

                     sprintf(words[*idx].lines,"%d,",line);





        (*idx)++;

    skipdup:

        if (*idx == MAXW) { /* check 'idx' against MAXW */
            fprintf (stderr, "warning: MAXW words exceeded.\n");
            break;
        }


    if(now=='\n'){
        line++;
    }
    continue;
    }
    now=tolower(now);
    word[j]=now;
    word=realloc(word,(j+1+1)*sizeof(char));

    }






    fclose (fp);

    return 0;
}

/* qsort compare funciton */
int compare (const void *a, const void *b)
{
    wfstruct *ap = (wfstruct *)a;
    wfstruct *bp = (wfstruct *)b;
    return (strcmp (ap->seen, bp->seen));
}

Answer 1

首先，请格式化您的代码，其次 - 使用 fopen() 打开文件后，您尝试使用 getchar() 读取它。这是行不通的，因为 getchar() 从 stdin 读取。要从使用 fopen() 打开的文件中读取字符，您应该使用 fgetc()。

http://www.cplusplus.com/reference/cstdio/fgetc/

在函数 get_word_freq() 中将 now=getchar(); 更改为 now=fgetc(fp);