Collection of 37 quick programming exercises

Echo printing

Ask the user to input anything and then output it back. This is often referred to as echo printing.

Variable swapping

Create two variables x and y in a program and then swap their values.

Addition calculator

Ask the user to input two numbers. Add these two together and then output the result back.

String length

Ask the user to input anything and then output the length of the input (which is a string).

Blank spaces

Ask the user to input anything and then count the number of blank spaces in it. Output this back.

Sorted array

Create an array of numbers (whatever you like), then sort it, and finally print it. The array should be modified in-place.

Sum of positive integers

Given a positive integer n, sum all positive integers less than or equal to n. For example, if n = 10, the result would be 55.

Linear search

Create an array of numbers and a variable val holding any number that you like. Find whether val exists in the array or not, using linear search (that is, iterating over the entire array until you find a match).

Iterative factorial

Given a non-negative n, compute its factorial using a for loop. (I call this an iterative factorial.)

Palindrome check

Given a string, determine whether it is a palindrome or not. A palindrome is a string that reads the same way forwards and backwards. For example, "civic" is a palindrome because it reads as "civic" in reverse. But "good" is not a palindrome because it reads as "doog" in reverse.

Exam grade

Given the score achieved by a student in an exam, determine the corresponding grade. Here are the grade thresholds you should use:

• 90 or above: "A+"
• 80 to 90 (exclusive): "A"
• 70 to 80 (exclusive): "B"
• 60 to 70 (exclusive): "C"
• Below 60: "F"

For example, if the score is 79.5, the grade is "B."

Price after discount

Given an item's price in dollars (stored in a variable) and a discount, given as a percentage value (e.g. 50, meaning ::50\%::), determine the price after discount. Output it, rounded to 2 decimal places.

For example, if the price is 10.5 and the discount is 50, then output something like this:

$5.25

Digit character

Given a character, output "Digit" if it's a digit (0 - 9) or else "Not a digit."

Student bundles

Given the number of students n in a school, you have to determine how many 5-book bundles you need to order so that one book can be given to each student. For example, if there are 31 students, then you need 7 bundles (not 6 bundles because then you'll have only 30 books).

Time span

Given a time span in seconds, for e.g. 70, express it as a combination of hours, minutes, and seconds, as follows:

Hours: <hrs>
Minutes: <mins>
Seconds: <secs>

Readable time span

Extending the previous exericse, now express the time span in one line, just like you'd do so when writing out the time span. For example, 70 becomes "1 min 10 secs."

If hours, minutes, or seconds, anyone of these are zero, you should NOT include it in the output. For example, 60 (seconds) should be expressed as "1 min." Similarly, 3600 (seconds) should be expressed as "1 hr."

More simplified time span

Extend the previous exercise once again, this time omitting all lower components if a larger one is non-zero. For example, if the time span is "3 mins 2 secs" then just write "3 mins."

This also means that you must round the highest non-zero time component. For example:

• "3 mins 2 secs" is "3 mins".
• "3 mins 40 secs" is "4 mins" (because 40 is larger than 30).

User confirmation

Create a function to ask the user to enter a "yes" or "no" for confirming something (imagine that this is part of a larger program where you want to get the user's confirmation before doing something) and then return a Boolean likewise.

If the user enters "y" or "n", take it just like a "yes" or "no". If the user enters nothing, or enters anything other than these four values, take it as a "no."

User confirmation, default configurable

Extend the previous program so that you can configure the function to choose a default of your liking. For example, if you want the input to default to a "Yes" in case the user enters nothing or enters something out of the range of the four possible values, then you can provide true to the function.

Minimum number

Given an array of numbers, find the minimum number. In case the array is empty, just use a nullish value (in your language) as the minimum.

Bitwise NOT string

Given a string consisting of 0s and 1s — known as a bit string — compute its bitwise NOT operation, where each 1 becomes a 0 and each 0 becomes a 1. For example, given '1011', you get '0100'.

Random integer

Generate a random integer in a given range ::[a, b]:: (this is interval notation).

Float holding integer

Given a floating-point value, determine whether it holds an integer in it or not. For example, 70.0 holds an integer whereas 70.1 does NOT.

Multiplication table

Given an integer n, print its multiplication table from 1 to 10 as follows:

3 x 1 = 3
3 x 2 = 6
...
3 x 9 = 27
3 x 10 = 30

Array reverse

Given an array of items, reverse the array in-place.

Path segments

Given a Unix filesystem path, like /home/music, in a string, extract the individual path segments in an array. For example, given the path '/home/music', you should get the array:

['home', 'music']

Assume that the path might end at "/" (e.g. /home/music/, in which case the path segments are still "home" and "music") and that there is no contiguous repetition of "/" in the path.

Rudimentary calculator

Ask the user to input two numbers and then input a letter representing an operation that he wants to perform on them. For now, just stick to four operations: addition, subtraction, multiplication, and division. The letters that correspond to these are "a," "s," "m," and "d," respectively.

Validate integer

Create a function to accept a string that is comprised entirely of an integer (this is usually called a stringified integer), e.g. '-50', and then return a Boolean indicating whether it's an integer or not.

For example, '-50' indeed represents a valid integer (in the string). However, '-50s' is NOT a valid integer. Any other type apart from a string must be rejected (i.e. return a Boolean false for it).

Validate integer loop

Ask the user to input an integer and keep asking him again and again if the entered input is invalid. You should, of course, use the function created in the previous exercise for this.

OTP code

Generate a random 4-digit OTP (one-time password) string, usually used to authorize operations in applications. For example, '0038'.

Manual uppercasing

Given a string consisting only of alphanumeric characters, create a function to uppercase the string. Handle the uppercasing manually.

For this exercise, I recommend you to search for how to get the character code of each character in the given string, and also how to go from the character code of a lowercase character to its corresponding uppercase character.

Letter frequency

Given a piece of text, determine the frequency of all the 26 English alphabet letters in it and output something as follows:

a: <count>
b: <count>
c: <count>
...
y: <count>
z: <count>

You must use an array to solve this problem.

Hyphenated words

Ask the user to input a hyphenated word, i.e. containing the hyphen (-) character, and then display each constituent word out on the document, one-by-one. If the input doesn't contain a hyphen, produce an error message to the user and ask for the input again.

For example, if the user inputs "new-line," the program must output "new" and "line." But if the user inputs "hello," since there is no hyphen in the input, print something like "Invalid input" and then prompt him to input again.

Arithmetic again

Combine the Addition calculator and User confirmation exercises to continuously perform addition of two given numbers until the user asks to exit the loop.

Binary, octal, and hex

Given an integer n, output it in binary, octal, and hexadecimal representations. These representations must be prefixed with "0b," "0o," and "0x" respectively. For example, the binary representation "0b1001" should be produced for the decimal integer 9.

String representation

Given a string, output it with single quotes (') around it. If the string itself contains single quotes in it, precede them with a backslash (\). If the string contains a backslash, precede it with another backslash.

For example, shown below are the outputs for the strings 'hello' and "he's doing good":

'hello'
'he\'s doing good'

Balanced braces

Given a string containing, or possibly even not containing, left and right curly braces ({ and }), determine whether they are balanced or not.

"Balanced" here means that a right curly brace does NOT appear before a preceding left curly brace, and also that each left curly brace is balanced by a corresponding right curly brace.

For example, the following is balanced:

This is { balanced }

But the following three lines are not:

This is } not balanced {
This is } not balanced
And { this isn't either

In case the string doesn't contain any brace at all, consider it balanced.