Array changing first value without explicitly modifying it when calling fscanf

I am reading a value from std in and storing it in an array min[3] and later on proceed to make an array comparison. Somin is never touched before the comparison.

After debugging, I noticed that min[0] changes from the input value to \0 upon the executon of this line:

fscanf(locDayFile, "%s", extractedHour);

where locDayFile and extractedHour are declared as such:

FILE* locDayFile;
char extractedHour[3];

Any ideas on what is going wrong ?

EDIT Here I am posting the code:

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

struct coords{
    float coord[3];
    char station[5];
    struct coords *next;
};

void Add(struct coords**,char*, float*);
float* Get(struct coords*, char*);

int main(){

    DIR *rootFolder, *subFolder;
    struct dirent *rootEnt, *subEnt;
    char rootFolderName[260], subFolderName[260];

    FILE *locDayFile,  *headers, *coordFile;
    FILE *stationDay, *yearDay, *time, *reference;
    char locDayFileName[260], headersFileName[260], coordFileName[260];
    char stationDayName[260], yearDayName[260], timeName[260], referenceName[260];
    char result[260];
    char make[260];

    char readLine[256];

    char searchingFolderName[9], folderCmp[9];

    char location[7], year[5], day[4], hour[3], min[3], referenceStation[5];
    char locationTest[7], dayTest[4];
    char extractedStation[5], extractedYear[5], extratedDay[4], extractedHour[3], extractedMin[3];
    char rms[7];
    float delay, refereDelay = 0;
    float *coordinates;

    char choice;

    printf("Please enter the following information:\n");
    printf("Location: ");
    scanf("%s", location);
    memmove(location+1, location, 4);
    location[0] = 'o';
    location[5] = 'a';
    location[6] = '\0';
    printf("Year: ");
    scanf("%s", year);
    printf("Day: ");
    scanf("%s", day);

    sprintf(searchingFolderName, "%s_%s", year, day);

    hour[0] = '\0';
    min[0] = '\0';
    referenceStation[0] = '\0';
    referenceName[0] = '\0';
    printf("Do you wish to enter the time?(Y/N): ");
    do{
        scanf("%c", &choice);
    }while(choice != 'Y' && choice != 'y' && choice != 'N' && choice != 'n');
    if(choice == 'Y' || choice == 'y'){
        printf("Hour: ");
        scanf("%s", hour);
        printf("Minutes: ");
        scanf("%s", min);
    }
    printf("Do you wish to enter a reference station?(Y/N): ");
    do{
        scanf("%c", &choice);
    }while(choice != 'Y' && choice != 'y' && choice != 'N' && choice != 'n');
    if(choice == 'Y' || choice == 'y'){
        printf("Reference station: ");
        scanf("%s", referenceStation);
    }

    printf("Root folder path: ");
    scanf("%s", rootFolderName);

    struct coords *c;
    c = NULL;

    printf("Coordinates file path: ");
    scanf("%开发者_运维技巧s", coordFileName);
    coordFile = fopen(coordFileName, "r");
    if(coordFile != NULL){
        char st[5];
        float coords[3];
        while(!feof(coordFile)){
            fscanf(coordFile, "%s", st);
            fscanf(coordFile, "%f", &coords[0]);
            fscanf(coordFile, "%f", &coords[1]);
            fscanf(coordFile, "%f", &coords[2]);

            Add(&c, st, coords);
        }
    }

    if((rootFolder = opendir(rootFolderName)) != NULL){
        while((rootEnt = readdir(rootFolder)) != NULL){

            sprintf(result, "%sresults/", rootFolderName);
            sprintf(make, "mkdir -p %s", result);
            system(make);

            folderCmp[0] = '\0';
            strncpy(folderCmp, rootEnt->d_name, 8);
            folderCmp[8] = '\0';

            if(strcmp(folderCmp, searchingFolderName) == 0){

                sprintf(subFolderName, "%s%s/", rootFolderName, rootEnt->d_name);

                if((subFolder = opendir(subFolderName)) != NULL){
                    while((subEnt = readdir(subFolder)) != NULL){

                        strncpy(locationTest, subEnt->d_name, 6);
                        locationTest[6] = '\0';
                        strncpy(dayTest, (subEnt->d_name)+7, 3);
                        dayTest[3] = '\0';
                        if((strcmp(location, locationTest) == 0) && (strcmp(day, dayTest) == 0)){

                            sprintf(locDayFileName, "%s%s", subFolderName, subEnt->d_name);
                            locDayFile = fopen(locDayFileName, "r");

                            while(!feof(locDayFile)){

                                char garbage[25];

                                fscanf(locDayFile, "%s", garbage);
                                if(strcmp(garbage, "ATM_ZEN") == 0){

                                    sprintf(headersFileName, "%sheaders_%s-%s", rootFolderName, year, day);
                                    headers = fopen(headersFileName, "a+");

                                    fscanf(locDayFile, "%s", garbage);

                                    fscanf(locDayFile, "%s", extractedStation);//3rd column.
                                    fprintf(headers, "%s\t", extractedStation);

                                    fscanf(locDayFile, "%s", garbage);

                                    fscanf(locDayFile, "%s", extractedYear);//5th column.
                                    fprintf(headers, "%s\t", extractedYear);

                                    fscanf(locDayFile, "%s", garbage);

                                    fscanf(locDayFile, "%s", extratedDay);//7th column.
                                    fprintf(headers, "%s\t", extratedDay);

                                    fscanf(locDayFile, "%s", extractedHour);//8th column.
                                    fprintf(headers, "%s\t", extractedHour);

                                    fscanf(locDayFile, "%s", extractedMin);//9th column.
                                    fprintf(headers, "%s\t", extractedMin);

                                    fscanf(locDayFile, "%s", garbage);
                                    fscanf(locDayFile, "%s", garbage);

                                    fscanf(locDayFile, "%f", &delay);//12th column.
                                    fscanf(locDayFile, "%s", rms);//13 column.
                                    fprintf(headers, "%s\t", rms);
                                    fprintf(headers, "%f\n", delay);

                                    if(strcmp(referenceStation, extractedStation) == 0 && refereDelay == 0)
                                        refereDelay = delay;


                                    coordinates = Get(c, extractedStation);
                                    if(coordinates != NULL){
                                        //station_day file
                                        sprintf(stationDayName, "%s%s_%s", result, extractedStation, extratedDay);
                                        stationDay = fopen(stationDayName, "a+");
                                        fprintf(stationDay, "%s\t", extractedYear);
                                        fprintf(stationDay, "%s\t", extractedHour);
                                        fprintf(stationDay, "%s\t", extractedMin);
                                        fprintf(stationDay, "%f\t", coordinates[0]);
                                        fprintf(stationDay, "%f\t", coordinates[1]);
                                        fprintf(stationDay, "%f\t", coordinates[2]);
                                        fprintf(stationDay, "%s\t", rms);
                                        fprintf(stationDay, "%f\n", delay);
                                        fclose(stationDay);

                                        //year_day file
                                        sprintf(yearDayName, "%s%s_%s", result, extractedYear, extratedDay);
                                        yearDay = fopen(yearDayName, "a+");
                                        fprintf(yearDay, "%s\t", extractedStation);
                                        fprintf(yearDay, "%s\t", extractedHour);
                                        fprintf(yearDay, "%s\t", extractedMin);
                                        fprintf(yearDay, "%f\t", coordinates[0]);
                                        fprintf(yearDay, "%f\t", coordinates[1]);
                                        fprintf(yearDay, "%f\t", coordinates[2]);
                                        fprintf(yearDay, "%s\t", rms);
                                        fprintf(yearDay, "%f\n", delay);
                                        fclose(yearDay);

                                        //year_day_hour_min file
                                        if((hour[0] != '\0' && (strcmp(hour, extractedHour) == 0)) && (min[0] != '\0' && (strcmp(min, extractedMin) == 0))){
                                            sprintf(timeName , "%s_%s_%s", yearDayName, hour, min);
                                            time = fopen(timeName, "a+");
                                            fprintf(time, "%s\t", extractedStation);
                                            fprintf(time, "%f\t", coordinates[0]);
                                            fprintf(time, "%f\t", coordinates[1]);
                                            fprintf(time, "%f\t", coordinates[2]);
                                            fprintf(time, "%s\t", rms);
                                            fprintf(time, "%f\n", delay);
                                            fclose(yearDay);
                                        }
[.....]

---

You haven't shown us enough, so it's purely a guess, but the input you're reading into extractedHour is probably three characters long, and you've defined the array as 3 characters, leaving no room for the NUL terminator.

You've probably defined min immediately after extractedHour, so when you write past the end of extractedHour, it ends up writing the NUL terminator into the next memory, which happens to be min.

---

Without a bit more information, my guess is locDayFile contains a string that is more than 3 bytes. When you make your fscanf call, it overwrites more memory than you think it should. Try allocating a larger buffer to extractedHour (instead of 3, make it like 64) and let us know what happens. If that fixes the problem, you might need to first fix your locDayFile, then fix your fscanf call, rather than using %s, use %2s, this tells scanf (and it's variants) that you only want it to read a string with a maximum # of 2 characters. This will avoid a buffer over-run. Another option, is to use %as... which is used to allocate a string (scanf will allocate however many bytes it needs to store the string).

Example:

char *str;
fscanf(in_file, "%as", &str);  //Notice the & here!
//Not covered is calling free(str)
//But you must check if fscanf was successful
//before freeing str

Example 2:

char str[3];
fscanf(in_file, "%2s", str);  //Notice this doesn't use &
//No need to deallocate, and it will not buffer overrun on you!

If this doesn't fix your program, give us a bit more info.

---

Sorry, I can only give stylistic remarks.

1) divide and conquer: split the code up into logical functions, each doing only one thing. This will also make it easier to test the separate parts without too much interference.

2) feof() does not do what you think it does.

3) Parsing text files is easier if you first read in entire lines (eg with fgets()) and than split them up into fields. It is also less vulnerable to bufferoverflow.

4) gets() is a recipe for disaster. So is scanf() in the form you are using it.