Problems
Practice problems and exercises.
1. Largest and smallest using pointers
Write a program that takes N numbers, stores them in an array, and prints the largest and smallest using pointers.
2. Armstrong numbers 1–500
Find and print all Armstrong numbers between 1 and 500.
3. Sum of positives and negatives from file
Open a file of integers and print separate sums of positives and negatives.
4. Factorial from 1 to n
Take n and print factorials for 1 to n using a for loop.
5. Prime check for N test cases
For each of N inputs, check if the number is prime (loop based).
6. Swap without third variable
Swap two numbers using arithmetic operators only.
7. Sum of primes 1–50
Print the sum of all prime numbers between 1 and 50.
8. Write 1–10 to file and sum
Create output.txt, write 1–10, then reopen and compute their sum.
9. Palindrome string (no string.h)
Read a string and print whether it is a palindrome without using string library functions.
10. Merge two arrays
Merge arrays of size m and n into a third array and print it.
11. Hollow square pattern
Draw a hollow square of side length n using '*'.
12. AP terms (a=5, d=3)
Generate the first 20 terms of the AP where a=5 and d=3.
13. Perfect numbers 1–500
Display all perfect numbers between 1 and 500.
14. Count vowels
Take a string and count the number of vowels.
15. Stats from mixed-number file
Read integers/floats/doubles until EOF; print count, sum, min, max, average.
16. Even/odd sum using conditional operator
Check whether the sum of two integers is even or odd using ?: .
17. Count positives, negatives, zeros
Read an integer array; count positives, negatives, and zeros.
18. Recursive sum of digits
Compute the sum of digits of an integer using recursion.
19. Highest mark and average from file
Read Name–Marks pairs; print the student with highest mark and the average mark.
20. Reverse array in place
Reverse an integer array in place without a second array.
21. Rotate array right by one
Rotate elements of an array to the right by one position.
22. Multiplication table
Print the multiplication table of a number using a for loop.
23. Recursive GCD
Compute the GCD of two integers using recursion.
24. Sign of product using conditional operator
Read three integers; determine if their product is positive, negative, or zero using ?: .
25. Divisibility using conditional operator
Check whether the first number is divisible by the second using ?: .
26. Binary of integer (no arrays/strings)
Print the binary representation of an integer using loops and division/modulus only.
27. Count uppercase and lowercase
Read a string and count uppercase and lowercase letters separately.
28. Reverse integer using recursion
Find the reverse of an integer using recursion.
29. Diamond pattern
Print a diamond pattern for input size 5.
30. Remove duplicates from array
Read an array of integers; remove duplicate values and print the updated array.