Question

this is my struct

   typedef struct {
        char mmsi[10];
        char name[20];
        double latitude;
        double longitude;
        int course;
        double speed;
    }Vessel;

this is my function which doesnt want to work

void searchByLatLong(double latitude, double longitude){
        FILE * file;
        struct dirent *drnt;
        DIR * dir = opendir("./text");
        char *path = (char *)malloc(19);
        Vessel *vessel = (Vessel *)malloc(sizeof(Vessel));

        while((drnt = readdir(dir)) != NULL) {
            if(strcmp(drnt->d_name,".") && strcmp(drnt->d_name,"..")) {

                strcpy(path,"text/");
                strcat(path,drnt->d_name);

                file=fopen(path, "r");
                fscanf(file," %s %[a-zA-Z0-9 ]19s %lf %lf %d %lf", &vessel->mmsi,&vessel->name,&vessel->latitude,&vessel->longitude,&vessel->course,&vessel->speed);

        //  if (mmsi+".txt" == drnt->d_name){
                    printf("%s\n%s\n%lf\n%lf\n%d\n%lf\n\n",vessel->mmsi,vessel->name,vessel->latitude,vessel->longitude,vessel->course,vessel->speed);
            //}


            fclose(file);
        }
        seekdir(dir, telldir(dir)); 

    //  if(this->mmsi == mmsi){
        //  printVessel();
    //  }

    }
    closedir(dir);
}

When i try to load txt file it loads only two first strings then after it theres some rubbish from memory. Loading the data to another variables changes nothing ;/
This is a sample txt file which should be loaded:

3
RMS Titanic
22.222
33.333
4
5.9

Answer 1

The problem is with your format string. The correct format string is:

" %s %19[a-zA-Z0-9 ] %lf %lf %d %lf"

The field width goes before the conversion specifier. Also, the […] sequence is a conversion specifier, just like ‘s’. The problem you’re seeing is that fscanf() processes the ‘3’ because it matches the first %s. Then it processes the ‘RMS Titanic’ because it matches %[a-zA-Z0-9 ] but then processing stops because there is no ’19s’ in the input. At this point the remaining arguments are uninitialized.

You should check the return value from fscanf(). It will tell you how many conversions were actually performed.