c - 在C中读取和打印文件

Question

好的，我正在尝试读取包含我的信息的文本文件。文本文件内容是这样的:

gasData.txt

0 987654 201200 4.000000
1 red 89114 0.000000
2 red 89712 13.500000
3 red 90229 15.300000
4 987654 201001 0.000000
5 987654 201111 5.200000
6 987654 201612 25.299999
7 red 89300 7.100000
8 green 16 0.000000
9 green 216 20.000000
10 green 518 61.000000
11 green 879 50.000000

代码

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>

#define N 12

struct record
{
    char id[7];
    int odometer;
    float gallons;
};
typedef struct record record_t;

record_t gasData[N];

int main(int argc, char *argv[])
{

    FILE *fileInput;
    float gallons;
    int element;
    char id[10], odometer[10];

    fileInput = fopen("gasData.txt", "r");

    for(element = 0; element < N; element++)
    {
        fscanf(fileInput, "%s %s %f", id, odometer, &gallons);

        /*if (feof(fileInput))
        {
            printf("end-of-file detected on file in\n");
            exit(1);
        }*/

        printf("element = %d:, id = %s, odometer = %s, gallons = %f\n", element, id, odometer, gallons);
    }

    exit (0);
}

输出

element = 0:, id = (, odometer = ₧j↑u►↓@, gallons = 0.000000
element = 1:, id = (, odometer = ₧j↑u►↓@, gallons = 0.000000
element = 2:, id = (, odometer = ₧j↑u►↓@, gallons = 0.000000
element = 3:, id = (, odometer = ₧j↑u►↓@, gallons = 0.000000
element = 4:, id = (, odometer = ₧j↑u►↓@, gallons = 0.000000
element = 5:, id = (, odometer = ₧j↑u►↓@, gallons = 0.000000
element = 6:, id = (, odometer = ₧j↑u►↓@, gallons = 0.000000
element = 7:, id = (, odometer = ₧j↑u►↓@, gallons = 0.000000
element = 8:, id = (, odometer = ₧j↑u►↓@, gallons = 0.000000
element = 9:, id = (, odometer = ₧j↑u►↓@, gallons = 0.000000
element = 10:, id = (, odometer = ₧j↑u►↓@, gallons = 0.000000
element = 11:, id = (, odometer = ₧j↑u►↓@, gallons = 0.000000

我说的是废话，这是我的程序输出。唯一有效的是元素，但这只是循环的计数，所以没有问题。此外，当我取消注释我的文件结束循环时，我的程序崩溃了。抱歉，我不知道如何编辑列表。在此先感谢您的帮助。

编辑代码

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>

#define N 12

/*struct record
{
    char id[7];
    int odometer;
    float gallons;
};
typedef struct record record_t;

record_t gasData[N];*/

int main(int argc, char *argv[])
{

    FILE *fileInput;
    float gallons;
    int element;
    char id[10]; char odometer[10];

    fileInput = fopen("gasData.txt", "r");
    if (fileInput == NULL)
        return -1;

    for(element = 0; element < N; element++)
    {
        if (fscanf(fileInput, "%9s%9s%f", id, odometer, &gallons) == 3)
        {
            printf("element = %d:, id = %s, odometer = %s, gallons = %f\n",
                element, id, odometer, gallons);
        }
    }

    exit (0);
}

Answer 1

您可能会溢出缓冲区并覆盖 '\0' 终止符试试这个

fscanf(fileInput, "%9s%9s%f", id, odometer, &gallons);

同时，检查 fscanf() 是否成功，否则值将未初始化并且会发生同样的事情

if (fscanf(fileInput, "%9s%9s%f", id, odometer, &gallons) == 3)
{
    printf("element = %d:, id = %s, odometer = %s, gallons = %f\n", 
        element, id, odometer, gallons);
}

不要假设事情会很顺利，还要检查 fopen() 没有失败

fileInput = fopen("gasData.txt", "r");
if (fileInput == NULL)
    return -1;

这段代码

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>

#define N 12

struct record
{
    char id[7];
    int odometer;
    float gallons;
};
typedef struct record record_t;

record_t gasData[N];

int main(int argc, char *argv[])
{

    FILE *fileInput;
    float gallons;
    int   element;
    char  id[10];
    char  odometer[10];

    fileInput = fopen("gasData.txt", "r");
    if (fileInput == NULL)
    {
        fprintf(stderr, "cannot open `gasData.txt'\n");
        return -1;
    }
    for(element = 0; element < N; element++)
    {
        if (fscanf(fileInput, "%9s%9s%f", id, odometer, &gallons) == 3)
        {
            printf("element = %d:, id = %s, odometer = %s, gallons = %f\n",
                element, id, odometer, gallons);
        }
    }

    return 0;
}

不应该失败。