从文本文件中读取一行并将数据用struct内的空格分隔 [英] Read a line from text file and place data separated by spaces inside struct

问题描述

我必须用C编写一个函数，该函数将文件指针作为输入并返回如下结构:

I've to write a function in C which takes as input a filepointer and returns a structure like this:

typedef struct product{
    char * code_product;
    char * name;
    char * code_piece;
    only_time_t enter;
    only_time_t exit;
}product_t;

此结构使用另一个这样的结构:

This struct uses another struct like this:

typedef struct only_time{
    int hour;
    int minute;
    int second;
}only_time_t;

为了从文件中读取，我使用了getline()函数，并且我使用了strtok()函数来创建令牌.这是我用来从文件中读取的功能:

In order to read from the file I use the getline() function and the I use the strtok() function to create tokens. Here is the function I use to read from the file:

product_t * read_line(FILE * fp){
    char * line = NULL;
    size_t len = 0;
    product_t * temp;
    int i = 0;

    temp = (product_t *) malloc(sizeof(product_t));

    temp->code_product = (char *) malloc(sizeof(char) * 4);
    temp->name = (char *) malloc(sizeof(char) * 60);
    temp->code_piece = (char *) malloc(sizeof(char) * 4);

    //read a line from the file
    getline(&line, &len, fp);

    //handle line info info
    char *tokens[80];

    tokens[0] = strtok(line," ,.");

    while (tokens[i] != NULL) {
        i++;
        tokens[i] = strtok(NULL," ,.");                             
    }

    temp->code_product = tokens[0];
    temp->name = tokens[1];
    temp->code_piece = tokens[2];
    temp->enter = timestring_to_time(tokens[3]);
    temp->exit = timestring_to_time(tokens[4]);

    //cleanup
    if (line)
        free(line);
    return(temp);
}

为了查看程序已读的内容，我使用了一个简单的函数来打印struct:

In order to see what the program has read I use a simple function which prints the struct:

void print_product(product_t * product){
    printf("product_t code_product: %s \n", product->code_product);
    printf("product_t name: %s \n", product->name);
    printf("product_t code_piece: %s \n", product->code_piece);
    printf("product_t enter: %d:%d:%d \n", product->enter.hour,product->enter.minute,product->enter.second);
    printf("product_t exit: %d:%d:%d \n", product->exit.hour,product->exit.minute,product->exit.second);
}

我已经设置了一个测试用例，该测试用例在文本文件中有以下行(称为test.txt，并与可执行文件位于同一文件夹中):

I have setup a testcase which has the following line in the text file (called test.txt and placed in the same folder as the executalble):

H235 Sportello_dx N246 15:20:43 15:27:55

H235 Sportello_dx N246 15:20:43 15:27:55

但是程序的输出是:

product_t code_product: ��)�� 
product_t name:  
product_t code_piece: N246 
product_t enter: 15:20:43 
product_t exit: 15:27:55 

这是一个粘贴程序，可以运行所有代码: https://pastebin.com/9rz0vM5G

here is a pastebin with the entire code ready to run: https://pastebin.com/9rz0vM5G

为什么我在前两行中得到了这个奇怪的输出，但是其余的仍在工作?

why am I getting this wierd output for the first 2 lines but the rest is working?

推荐答案

strtok()在解析字符串时会对其进行修改，并返回指向该字符串内部的指针(在您的情况下为line).因此，当您以后在free(line)中释放temp结构引用的内存.研究strdup().

strtok() modifies the string while it is parsed and returns pointers to inside that same string, in your case line. So when you later free(line) you free the memory the temp structure references. Research strdup().

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