Summary - Arrays
- C course
- Beginner
- Lesson 58/116
- 5 min
Use single and multidimensional arrays to write a grade table.
Summary - Arrays
In this section you learned array declaration, access, sizeof, multidimensional arrays and iterating with loops. Now we'll combine them in a grade table app.
The app holds a student's three exam grades in an array; computes the average and assigns a letter grade. It uses both a single-dimensional array and a for loop.
Practice Average of three grades
Write a C program. Declare int scores[3] = {80, 90, 70};. Initialize int sum = 0;. With for (int i = 0; i < 3; i++) do sum += scores[i];. Print the average with printf("Average: %d\n", sum / 3);. Put #include <stdio.h> at the top.
Starter code
#include <stdio.h>
int main(void) {
// Declare scores, sum with for, print the average
return 0;
}Sample solution
#include <stdio.h>
int main(void) {
int scores[3] = {80, 90, 70};
int sum = 0;
for (int i = 0; i < 3; i++) {
sum += scores[i];
}
printf("Average: %d\n", sum / 3);
return 0;
}Expected output
Average: 80
Practice Multidimensional grade table
Write a C program. Declare int grades[2][3] = {{80, 90, 70}, {85, 95, 75}}; (two students, three exams). Print the first student's first grade and the second student's last grade with printf("%d %d\n", grades[0][0], grades[1][2]);. Put #include <stdio.h> at the top.
Starter code
#include <stdio.h>
int main(void) {
// Declare the grades matrix, print two elements
return 0;
}Sample solution
#include <stdio.h>
int main(void) {
int grades[2][3] = {{80, 90, 70}, {85, 95, 75}};
printf("%d %d\n", grades[0][0], grades[1][2]);
return 0;
}Expected output
80 75
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 How is the average of three grades computed?
int scores[3] = {80, 90, 70};
int sum = 0;
for (int i = 0; i < 3; i++) sum += scores[i];- scores[0]
- sum * 3
- sum / 3 Correct answer
- 3 / sum
Explanation: The sum is divided by the count.
2 Complete the array declaration
int ____[3] = {80, 90, 70};int scores[3] = {80, 90, 70};Explanation: scores is the array name.
3 Match the array concepts
| Term | Meaning |
|---|---|
int scores[3] |
Array declaration |
scores[0] |
First element |
sizeof |
Byte measure |
sum += scores[i] |
Accumulation |