Adding 3 basic features to my existing code [closed] - c

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I have a gradebook program that I've been building, which works fine, but now I want to slot 3 new functions into the existing code. I can't wrap my brain around the logical path I need to take to make it work. I need a SIMPLE way to also get the highest, lowest, and average grades printed at the end. Here's my program...
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#define MAX_GRADE_COUNT 200
int main() {
int grade[MAX_GRADE_COUNT];
int i;
int count = 0;
char continueResponse;
printf("Welcome to Gradebooker!\n\n");
for(i = 0; i < MAX_GRADE_COUNT; i++) {
printf("Please enter grade (0-100): ");
scanf(" %d", &grade[i]);
count++;
printf("Do you have more grades to enter?(Y/N): ");
scanf(" %c", &continueResponse);
if(toupper(continueResponse) != 'Y') {
printf("\n >> Thank you for using Gradebooker! <<\n");
break;
}
}
printf("\n\nCurrent Gradebooker listings: \n\n");
for(i = 0; i < count; i++) {
printf("\t%5d\n", grade[i]);
}
return 0;
}

Answer 1

The program would need to calculate the max, min and average in the second loop, like this:
int sum = 0;
int minimum = INT_MAX;
int maximum = 0;
for(i = 0; i < count; i++) {
printf("\t%5d\n", grade[i]);
sum += grade[i];
if(grade[i] < minimum) minimum = grade[i];
if(grade[i] > maximum) maximum = grade[i];
}
float average = (float)sum / count;
printf("min grade: %d\n", minimum);
printf("max grade: %d\n", maximum);
printf("average: %f\n", average);
The minimum starts with a value that is larger than all values in the list (INT_MAX for example is the largest possible value an int can take). Then, for each grade in the array, it replaces it with that grade, if it is smaller than the one currently in the minimum variable. That way minimum will in the end contain the smallest grade.
Same for maximum, but reversed.
For the average, it accumulates the sum of all grades (sum needs to be initialized to 0 at the beginning), and the divides it by the number of grades in the end. This gives an arithmetic mean in average.
Using float, it calculates the average as a floating point number (so the average can be non-integer). The (float)sum / count is needed so that it will first cast (convert) sum to a float, and so a floating point division on it. Otherwise, with sum / count is would do an integer division (which returns a rounded down integer), and store that as float in the average variable afterwards.

Answer 2

The idea for finding maximum value is: first declare a variable (lets say, MAXX) to store maximum value and initial it with as minimum value as possible and then iterate through the array and if any value in the array found greater then the current value of MAXX variable than update the value of MAXX with the value.
The idea for finding minimum value is: first declare a variable (lets say, MINN) to store minimum value and initial it with as maximum value as possible and then iterate through the array and if any value in the array found greater then the current value of MINN variable than update the value of MINN with the value.
Idea for finding avarage: Sum all the grade and then divide the sum with the number of grade.
See the implementation below for better understanding:
int max_grade = 0;//for storing maximum grade
/*
Minimum possible value should be initialize here.
Best option to write here is:
int max_grade = INT_MIN;
But to use INT_MIN <limits.h> file must be included.
*/
int min_grade = 10000000;//for storing maximum grade
/*
Maximum possible value should be initialize here.
Best option to write here is:
int min_grade = INT_MAX;
But to use INT_MAX <limits.h> file must be included.
*/
int total_grade = 0;//for counting all the grade
for(i = 0; i < count; i++) {
if(grade[i] > max_grade){
max_grade = grade[i];
}
if(grade[i] < min_grade){
min_grade = grade[i];
}
total_grade += grade[i];
}
printf("Max grade = %d\n" max_grade);
printf("Min grade = %d\n" min_grade);
printf("Avg grade = %d\n" total_grade/count);

Answer 3

I could not see all your code (it seemed to be cut off at the bottom), however the basically procedure to get an average, max and min in C is as follows:
int running_total = 0;
int count_grades = 0;
int max_so_far = 0;
int min_so_far = 999;
while( -1 ){ // infinite loop
// get input (a grade)
// if input is done, break
count_grades++;
running_total += iCurrentGrade; // (iCurrentGrade should be defined during input phase)
if( iCurrentGrade > max_so_far ) max_so_far = iCurrentGrade;
if( iCurrentGrade < min_so_far ) min_so_far = iCurrentGrade;
}
printf( "avg: %d min: %d max: %d\n", (int)(running_total / count_grades), min_so_far, max_so_far );