For/while loop doesn't update value properly - c

Question

I'm trying to write a program which finds the weighted average (for grades and such).
Through user input, I create two arrays of the same size, one carrying the weights for each grading category, and the other holding the users score in the corressponding category. For example, if a student has a score of 92% in category 1, which is worth 30% of the total grade, then weights[1] = .3 and scores[1] = .92. This way, the average in each category can be found through (weights[i] * scores[i]) where i is an instance variable initialized in a for loop to go through each array entirely. The problem here is in finding the cumulative average- my program is written to compound the values of each average it handles for example I have tried code like average = average + (weights[i] * scores[i]) to obtain the final cumulative average. However through print statements I've found the value of average is set to the last (weights[i] * scores[i]) operation performed, ignoring the previous value of average (or taking it to be 0). For example, if weights[]={.3, .3, .4} and scores[] = {.4, .4 , .4}. The cumulative average should be .4, but my program tells me .32, which is the last value of weights times the last value of scores.
methods.c:
#include <stdio.h>
#include "methods.h"
int howManyCategories()
{
int categories = 0;
int firstTime = 0;
while(1)
{
if(firstTime == 0)
{
fprintf(stdout, "\nHow many categories are you currently graded on? ");
scanf("%d", &categories);
}
else
{
fprintf(stdout, "\nThat's not a valid value, try a positive integer. ");
scanf("%d", &categories);
}
firstTime++;
if(categories > 0)
{
return categories;
}
}
}
double howMuchWeight(int categories)
{
double weight = 0;
while(1)
{
if(categories == 1)
{
fprintf(stdout,
"\nThis %d category accounts for how much of your grade? (.1, .85, 1 etc.) ",
categories);
scanf("%lf", &weight);
}
else
{
fprintf(stdout,
"\nThese %d categories account for how much of your grade? (.1, .85, 1 etc.) ",
categories);
scanf("%lf", &weight);
}
if(weight > 1 || weight <= 0)
{
fprintf(stdout,
"\nRemember, total weighting must be positive and no larger than 1"
" (100 percent). \nTry Again.\n");
}
else
{
return weight;
}
}
}
double findWeightsAndScores(int i, double categories,
double checkWeights, double totalWeight,
double scores[])
{
while(1)
{
double piece = 0;
int count = i + 1;
fprintf(stdout, "\nWeight for category %d: ", count);
scanf("%lf",&piece);
if(piece > 0 && piece < 1)
{
findScores(i, &scores[i]);
return piece;
}
else
{
fprintf(stdout, "\nRemember, weights must be positive and less than 1!\n");
}
}
}
void findScores(int i, double scores[])
{
int validScore = 0;
while(validScore == 0)
{
int count = i + 1;
double score = 0;
fprintf(stdout, "Please enter your percentage score in category %d: ", count);
scanf("%lf", &score);
if(score >= 0 && score <= 1)
{
scores[i] = score;
validScore = 1;
}
else
{
fprintf(stdout, "\nRemember, scores in each category must be positive, no greater "
"than 1 (100 percent) and no less than 0, try again.\n\n");
}
}
}
double findAverage(int categories, double weights[], double scores[])
{
double average = 0;
for(int i = 0; i <= categories - 1; i++)
{
average += (weights[i] * scores[i]);
fprintf(stdout, "%lf", average);
}
return average;
}
methods.h:
#ifndef METHODS_H_
#define METHODS_H_
int howManyCategories();
double howMuchWeight(int categories);
double findWeightsAndScores(int i, double categories,
double checkWeights, double totalWeight, double scores[]);
void findScores(int i, double scores[]);
double findAverage(int categories, double weights[], double scores[]);
#endif
whatsmyGrade.c:
#include <stdio.h>
#include "methods.h"
int main()
{
while(1)
{
/*Prompts for categories*/
int categories = howManyCategories();
int dataProvided = 1;
double checkWeights = 0;
double grade = 0;
double average = 0;
/*Prompts for total weight*/
double totalWeight = howMuchWeight(categories);
double category[categories];
double weights[categories];
double scores[categories];
/*Assign weights to each category and score in each category*/
for(int i = 0; i <= categories - 1; i++)
{
/*Fill array for weights*/
weights[i] = findWeightsAndScores(i, categories, checkWeights, totalWeight,
scores);
checkWeights = checkWeights + weights[i];
if(checkWeights != totalWeight && i == categories - 1)
{
fprintf(stdout, "\nYour weight distribution is invalid! Try again.\n");
dataProvided = 0;
break;
}
}
/*Calculate total grade*/
if(dataProvided == 1)
{
average = findAverage(categories, weights, scores);
grade = (average / totalWeight) * 100;
fprintf(stdout, "Your cumulative average is %.2lf percent\n\n", grade);
return 1;
}
}/*End of parent while loop*/
}/*End of main*/
Thank you in advance

Answer 1

Your problem is somewhere else because it works like a charm for me:
#include <stdio.h>
double findAverage(int categories, double weights[], double scores[])
{
double average = 0;
int i;
for(i = 0; i <= categories - 1; i++) {
average += (weights[i] * scores[i]);
fprintf(stdout, "%lf ", average);
}
return average;
}
int main(void) {
// your code goes here
double average;
double grade;
int categories = 3;
double totalWeight = .3 + .3 + .4;
double weights[] = {.3, .3, .4};
double scores[] = {.4, .4, .4};
average = findAverage(categories, weights, scores);
grade = (average / totalWeight) * 100;
fprintf(stdout, "\nYour cumulative average is %.2lf percent\n\n", grade);
return 0;
}

Answer 2

Got it, when I call the findScores function in the findWeightsAndScores function I was passing it &scores[i] when I should have been passing it scores. Thanks guys