Question

I have seen “config” files(yes, text files) for various console applications that look like the following

<token> <value>

How would I go about parsing such a thing in C, where < value > could be a string, a letter or even an integer/float/double?

I read this question ” How do I parse a token from a string in C? ” where it is mostly recommended to use strtok, but also that it’s not thread-safe, and I am planning on spawning multiple threads(provided I am able to finish my application)

P.S
Here is an example of a token and a value

user username123
pass 123456

Ah, I forgot the tricky part. I must also be able to parse a token, which has multiple values either separated by a comma.

Answer 1

I think that fgets() and sscanf() are your friend:

int parseTokens(FILE *filePtr, char **tokens, char **values)
{
    int i = 0;

    char line[128];

    while (fgets(line, 127, filePtr)) {
        tokens[i] = malloc(64);
        values[i] = malloc(64);

        sscanf(line, "%s %s", tokens[i], values[i]);

        i++;
    }

    return i;
}

int main(void)
{
    char *tokens[20];
    char *values[20];

    FILE *filePtr = fopen("~/test.txt", "r");

    if (!filePtr)
    {
        fprintf(stderr, "Error opening file: %s", strerror(errno));
    }

    int count = parseTokens(filePtr, tokens, values);

    for (int i = 0; i < count; i++) {
        printf("%s %s\n", tokens[i], values[i]);

        free(tokens[i]);
        free(values[i]);
    }

    fclose(filePtr);
}