parser.c

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

#define MAX_LINE_LENGTH 255

typedef struct
{
    int exposureTime;
    int flashPin;
    int triggerPin;
    int lightPin;
    double disDropLight;
    double disLightCam;
} Config;

typedef struct
{
    char key[255];
    char value[255];
} KeyValuePair;

// declarations
void addToConfig(Config *config, KeyValuePair pair);
KeyValuePair getKeyValuePair(char line[MAX_LINE_LENGTH]);
Config readConfigFromFile();

int main()
{
    Config config = readConfigFromFile();

    printf("%s: %d\n", "exposureTime", config.exposureTime);
    printf("%s: %d\n", "flashPin", config.flashPin);
    printf("%s: %d\n", "triggerPin", config.triggerPin);
    printf("%s: %d\n", "lightPin", config.lightPin);
    printf("%s: %f\n", "disDropLight", config.disDropLight);
    printf("%s: %f\n", "disLightCam", config.disLightCam);

    return 0;
}

Config readConfigFromFile()
{
    FILE *file;
    Config config;

    file = fopen("init", "r");
    if (file == NULL)
    {
        perror("fopen()");
        return config;
    }

    // read config file line by line
    char line[MAX_LINE_LENGTH];
    while (fgets(line, MAX_LINE_LENGTH, file))
    {
        // remove trailing newline
        line[strcspn(line, "\n")] = 0;

        // extract key value pair
        KeyValuePair pair = getKeyValuePair(line);

        // fill config struct
        addToConfig(&config, pair);
    }

    fclose(file);

    return config;
}

KeyValuePair getKeyValuePair(char line[MAX_LINE_LENGTH])
{
    char *delimiter = " ";
    KeyValuePair pair;

    int currentToken = 0; // ugh, i hate that - but I need to know which token I'm at and couldn't find a nicer way
    for (char *token = strtok(line, delimiter); token != NULL; token = strtok(NULL, delimiter))
    {
        // take the first token as key ...
        if (currentToken == 0)
        {
            strcpy(pair.key, token);
        }
        // ... and the second as value ...
        else if (currentToken == 1)
        {
            strcpy(pair.value, token);
        }
        // ... and ignore all other tokens.
        else
        {
            break;
        }

        currentToken++;
    }

    return pair;
}

void addToConfig(Config *config, KeyValuePair pair)
{
    if (strcmp(pair.key, "exposureTime") == 0)
    {
        config->exposureTime = atof(pair.value);
    }
    else if (strcmp(pair.key, "flashPin") == 0)
    {
        config->lightPin = atof(pair.value);
    }
    else if (strcmp(pair.key, "triggerPin") == 0)
    {
        config->triggerPin = atof(pair.value);
    }
    else if (strcmp(pair.key, "lightPin") == 0)
    {
        config->lightPin = atof(pair.value);
    }
    else if (strcmp(pair.key, "disDropLight") == 0)
    {
        config->disDropLight = atof(pair.value);
    }
    else if (strcmp(pair.key, "disLightCam") == 0)
    {
        config->disLightCam = atof(pair.value);
    }
    else
    {
        printf("unknown config key: %s\n", pair.key);
    }
}