Thread: file pointer and loops

I can't seem to get my program to read in my .txt file correctly and apply the loops to sort the information. I'm not just getting wrong answers back, they're all error returns. Can anyone tell what's going on wrong here?

Code:

#include <stdio.h>


int main(){
    // Initialize variables
    char fileName [20];
    int SIZE, bestRatingID, bestCostID, bestBatteryID, i;
    double bestCost, bestRating, bestBattery;
    // User prompt
    printf ("What is the name of the file?\n");
    scanf ("%s", &fileName);
    // Initialize file pointer
    FILE *ifp = fopen (fileName, "r");
    // Search for file length
    fscanf (ifp, "%d", &SIZE);
    // Initialize variables that rely on SIZE
    int manufacturingID [SIZE];
    double efficiencyRating [SIZE], cost [SIZE], batteryLife [SIZE];
    // Initialize for loop to scan whole document
    for (i = 0; i < SIZE; i++){
    fscanf (ifp, "%d %f %f %f", &manufacturingID [i], &cost [i], &efficiencyRating [i], &batteryLife [i]);
    //For loop to determine best values
    for (i = 0; i < SIZE; i++){
        // if statement for best cost assignment
        bestCost = cost [0];
        if (cost [i] < bestCost){
            bestCost = cost [i];
            bestCostID = manufacturingID [i];
        }
        // if statement for best efficiency rating
        bestRating = efficiencyRating [0];
        if (efficiencyRating [i] > bestRating){
            bestRating = efficiencyRating [i];
            bestRatingID = manufacturingID [i];
        }
        // if statement for best battery life
        bestBattery = batteryLife [0];
        if (batteryLife [i] > bestBattery){
            bestBattery = batteryLife [i];
            bestBatteryID = manufacturingID [i];
        }
    }
    // Final user output
    printf ("\nAttribute \t Best Option \t Best Value \n");
    printf ("Cost \t\t %d \t \t %f \n", bestCostID, bestCost);
    printf ("Efficiency \t %d \t \t %f \n", bestRatingID, bestRating);
    printf ("Battery \t %d \t \t %f \n", bestBatteryID, bestBattery);
    // if statement for when a robot is best in more than one category
    if (bestCostID == bestRatingID || bestCostID == bestBatteryID || bestBatteryID == bestRatingID)
        printf("\nRobot %d has the best rating in 2 or more attributes!\n", manufacturingID [i]);
    else
        printf("\n");
    // Close file pointer
    fclose (ifp);
return 0;
}

First, line 20:

Code:

for (i = 0; i < SIZE; i++){

is missing a closing brace (left curly brace) so the code you've supplied couldn't possibly even compile.

Second, you may want to review the documentation for scanf().

Code:

    
/* ... */
scanf ("%s", &fileName);   // &filename is a char**, but the scanf %s specifier wants a char*
/*... */
fscanf (ifp, "%d %f %f %f", &manufacturingID [i], &cost [i], &efficiencyRating [i], &batteryLife [i]); 
    // &cost[i] is a pointer to a double. %f wants a pointer to float. Ditto with the other two pointers you've supplied.

As an additional idea, it might have been nice to have a test file as well and a statement along the lines of what you expect the program to do compared to what it actually is doing (assuming the program compiles). Narrow down the bug by writing really short programs to try and reproduce the bug that you're experiencing; this can help find out what's going wrong. I think @laserlight has a good signature.