C Array Practice Solutions

These solutions use the same array topics listed on the main C arrays tutorial. The examples emphasize correct bounds, initialized variables and reusable loops.

1. Read Five Values Top ↑

#include <stdio.h>

int main(void) {
    int values[5];

    for (int i = 0; i < 5; i++) {
        printf("Enter value %d: ", i + 1);
        if (scanf("%d", &values[i]) != 1) {
            return 1;
        }
    }

    return 0;
}

2. Display All Elements Top ↑

for (size_t i = 0; i < count; i++) {
    printf("%d\n", values[i]);
}

3. Display Even Elements Top ↑

for (size_t i = 0; i < count; i++) {
    if (values[i] % 2 == 0) {
        printf("%d\n", values[i]);
    }
}

4. Sum All Elements Top ↑

int sum = 0;

for (size_t i = 0; i < count; i++) {
    sum += values[i];
}

5. Highest and Lowest Values Top ↑

int highest = values[0];
int lowest = values[0];

for (size_t i = 1; i < count; i++) {
    if (values[i] > highest) {
        highest = values[i];
    }
    if (values[i] < lowest) {
        lowest = values[i];
    }
}

Correction: maximum and minimum checks are independent. Using a broad else for the minimum can assign a value that is not actually the lowest.

6. Display in Reverse Order Top ↑

for (size_t i = count; i > 0; i--) {
    printf("%d\n", values[i - 1]);
}

7. Find Duplicate Values Top ↑

for (size_t i = 0; i < count; i++) {
    for (size_t j = i + 1; j < count; j++) {
        if (values[i] == values[j]) {
            printf("Duplicate: %d\n", values[i]);
            break;
        }
    }
}

8. Count Occurrences of a Value Top ↑

int target = 11;
int frequency = 0;

for (size_t i = 0; i < count; i++) {
    if (values[i] == target) {
        frequency++;
    }
}

9. Copy One Array to Another Top ↑

int copy[6];

for (size_t i = 0; i < count; i++) {
    copy[i] = values[i];
}

10. Sort in Descending Order Top ↑

#include <stdio.h>
#include <stddef.h>

int main(void) {
    int values[] = {0, 14, -11, 15, 11, -20};
    size_t count = sizeof values / sizeof values[0];

    for (size_t i = 0; i < count; i++) {
        for (size_t j = i + 1; j < count; j++) {
            if (values[i] < values[j]) {
                int temp = values[i];
                values[i] = values[j];
                values[j] = temp;
            }
        }
    }

    for (size_t i = 0; i < count; i++) {
        printf("%d ", values[i]);
    }
    printf("\n");
    return 0;
}

For ascending order, change the comparison from values[i] < values[j] to values[i] > values[j].

11. Print Unique Values Top ↑

for (size_t i = 0; i < count; i++) {
    int occurrences = 0;

    for (size_t j = 0; j < count; j++) {
        if (values[i] == values[j]) {
            occurrences++;
        }
    }

    if (occurrences == 1) {
        printf("%d\n", values[i]);
    }
}

← Arrays in C Two-dimensional arrays

Subhendu Mohapatra

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