在部分行上使用fread（）时，如何移动到下一行？

Question

我使用fread（）和fseek（）来收集字符串的一部分。我不是在整行上使用fread（）。

我会用整行，但据我所知，您不能在正确的字符数组上使用fseek（）吗？

`int parse(const char *f, const struct stat *flightD, int type){ 
//file pointer
Airport_S *Air_Pts = (Airport_S *)malloc(sizeoftype(Airport_S));
FILE *fp;
//char need[10];
char airLineFile[2];
char chkAirPt[3];
fp = fopen(f, "r");
if(type == FTW_F){ // test for 'type' of FTW_F
        //check to see if the file opened successfully
    if(fp == NULL)
        printf("Cannot open file %s", f)
        return 1;
        while (!(FEOF)){
            //fgets(need,10,fp)
            //must return zero to parent funtion to continue tree traversal
            // ?? While current dir != originally called dir?
            //open the file, read it's contents and assess them
            fseek(fp, 5, SEEK_SET) //set FP to right before airport code
            chkAirPt = fread(chkAirPt,sizeof(char),3, fp)
            fseek(fp,0,SEEK_SET);
            //combine the airline abbreviation with '.txt'
            airLineFile = strcat(fread(airLineFile, sizeof(char), 2,                               fp),".txt");
            //if the struct has no values in it, populate it with this first one.
            if(Air_Pts->airport == NULL){
                //Set info for very first node
                Air_Pts->airPt=strcpy(Air_Pts->airport, chkAirPt);
                fseek(fp,0,SEEK_SET);
                Air_Pts->fltInfo->airLine=airLineFile;
                Air_Pts->fltInfo->next = NULL;
                Air_Pts->fltInfo->prev = NULL;
                Air_Pts->next = NULL;
                Air_Pts->prev = NULL;
                //what is the file going to do after this?
            }
            else if(strcmp(Air_Pts->airport, chkAirPt) == 0){
                if(strcmp(Air_Pts->fltInfo->airLine, airLineFile) == 0){
                    Air_Pts->fltInfo->occ++; 
                }
                else
                    Air_Pts->fltInfo = addAirline(Air_Pts->fltInfo);        
            }

            // some code
            return 0;
        else //anything other than a file -or- FTW_D
            return 1;
            }
}

}`

Answer 1

您太努力了。只需读取并丢弃不需要的数据即可。例如：

/* Sample input line: AA43 DTW2315 ... */
/* Read first two columns of each line of a text file into a struct */

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

struct data {
        char airport[32];
        char flight[32];
        struct data *next;
};

FILE * Fopen(const char *path, const char *mode);
void * xmalloc(size_t);

void
push(struct data **head, struct data new)
{
        struct data *t = xmalloc( sizeof *t);
        t->next = *head;
        strncpy(t->airport, new.airport, sizeof t->airport);
        strncpy(t->flight, new.flight, sizeof t->flight);
        *head = t;
}

int
main(int argc, char **argv)
{
        FILE *ifp = argc > 1 ? Fopen(argv[1], "r") : stdin;
        struct data *head = NULL;
        struct data this;
        int line = 1;
        int c = 0;

        while( (c = fscanf(ifp, "31%s %31s", this.airport, this.flight)) == 2) {
                push(&head, this);

                /* Discard until the end of line */
                while( (c = fgetc(ifp)) != EOF ) {
                        if( c == '\n') {
                                line += 1;
                                break;
                        }
                }
        }

        /* Print all the records in reverse order */
        for( ; head; head = head->next ) {
                printf(" %s: %s\n", head->airport, head->flight);
        }
        return 0;
}


FILE *
Fopen(const char *path, const char *mode)
{
        FILE *rv = fopen(path, mode);
        if( rv == NULL ) {
                perror(path);
                exit(EXIT_FAILURE);
        }
        return rv;
}

void *
xmalloc(size_t s)
{
        void *rv = malloc(s);
        if( rv == NULL ) {
                perror("malloc");
                exit(EXIT_FAILURE);
        }
        return rv;
}