如何使用 C 解析 CSV 文件中的每一列

Question

I'm trying to use C to read a CSV file, iterate line by line (until EOF), and delimit/split each line by the comma. Then I wish to separate each column into "bins" and put add them to a struct (which isn't shown here; I defined it in a helper file) based on type.

For example, if I have 1,Bob , I'd like to split 1 and Bob into two variables. Here's what I've written so far.

void readFile(char file[25]) {
    FILE *fp;
    char line[1000];

    fp = fopen(file, "r"))

    while(fgets(line, 1000, fp)) {
        char* tmp = strdup(line);
        char* token;

        while((token = strsep(&tmp, ","))) {
            printf("%s\n", token);  // I want to split token[0] and token[1]
        }
    }
    fclose(fp);
}

T he above code does compile and run. I just don't know how to access each split of the token , like token[0] or token[1] . In python, this would be simple enough. I could just access 1 using token[0] and Bob using token[1] for each line . But here in C, I can't do that.

For testing purposes, all I'm doing right now is printing each line (in the second while loop), just to see how each split looks. I haven't implemented the code where I put each split line into its respective struct member.

I've searched Stack Overflow and found a multitude of threads on this topic. None of them seemed to help me except for this one , which I have drawn from. But I wasn't able to get the storing of split columns working.

Answer 1

In python, this would be simple enough. I could just access 1 using token[0] and Bob using token[1] for each line . But here in C, I can't do that.

Yes, you can, if only you define the array.

    while (fgets(line, sizeof line, fp))
    {
        char *tmp = strchr(line, '\n');
        if (tmp) *tmp = '\0';   // remove the '\n'
        tmp = strdup(line);
        #define MAXCOLUMNS  2
        char *token[MAXCOLUMNS];
        int c = 0;
        while (tmp)
        {
            if (c == MAXCOLUMNS) puts("too many columns"), exit(1);
            token[c++] = strsep(&tmp, ",");
        }
        if (1 <= c) printf("column 1: %s\n", token[0]);
        if (2 <= c) printf("column 2: %s\n", token[1]);
        // ONLY if the line's tokens are no longer needed:
        free(*token);
    }