fscanf and 2d array of integers

Question

disclaimer: I'm a struggling beginner

My assignment is to read integers from an input txt file into a 2D array. When i used printf's to debug/test my fscanf isn't reading the correct values from the file. i can't figure out why.

my code is as follows:

void makeArray(int scores[][COLS], FILE *ifp){
    int i=0, j=0, num, numrows = 7, numcols = 14;

    for(i = 0; i < numrows; ++i){
        for(j = 0; j < numcols; ++j){
            fscanf(ifp, "%d", &num);
            num = scores[i][j];
        }
    }
}

int main(){
    int scoreArray[ROWS][COLS];
    int i=0, j=0;
    FILE *ifp;
    ifp = fopen("scores.txt", "r");

    makeArray(scoreArray, ifp);

    system("pause");
    return 0;   
}

score 2 · Answer 1 · edited May 23 '17 at 12:06

2

You were assigning num (what you read from the file) into the value of the array scores[i][j] which is doing it backwards. The following code will read an arbitrary number of spaces in between each number, until it reaches the end of the file.

void makeArray(int scores[][COLS], FILE *ifp) {
    int i=0, j=0, num, numrows = 7, numcols = 14, ch;

    for (i=0; i < numrows; ++i) {
        for (j=0; j < numcols; ++j) {
            while (((ch = getc(ifp)) != EOF) && (ch == ' ')) // eat all spaces
            if (ch == EOF) break;                            // end of file -> break
            ungetc(ch, ifp);
            if (fscanf("%d", &num) != 1) break;
            scores[i][j] = num;                              // store the number
        }
    }
}

This Stack Overflow post covers this problem in greater detail.

edited May 23 '17 at 12:06

Community

1
1

answered Apr 10 '15 at 03:37

Tim Biegeleisen

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i changed what you suggested which was an error needing to be fixed but it is still not reading the correct integers from the file. there are 96 total integers in the input file with an unknown amount of spaces seperating them – Whittney Kirchmann Apr 10 '15 at 04:01
Please post what your input file looks like. – Tim Biegeleisen Apr 10 '15 at 04:03
See [this SO post](http://stackoverflow.com/questions/18737117/reading-values-from-csv-file-into-variables) for how to deal with reading a CSV file into C using `fscanf`. – Tim Biegeleisen Apr 10 '15 at 04:08
i posted it in the comments! thank u for your help i am reading that post now – Whittney Kirchmann Apr 10 '15 at 04:50
Please read [this post](http://stackoverflow.com/questions/3765023/how-do-i-read-white-space-using-scanf-in-c) as well. It is the one you want. – Tim Biegeleisen Apr 10 '15 at 04:54

fscanf and 2d array of integers

1 Answers1