C Online Test

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About the test

The C online test assesses knowledge of programming in the C language through a series of live coding questions.

The assessment includes work-sample tasks such as:

  • Using pointers to reference a location in memory.
  • Implementing and properly using data structures and algorithms.
  • Optimizing memory management and fixing memory leaks.

A good C developer needs a solid understanding of the C programming language and the implications of low-level optimizations to work on complex or performance critical code.

Sample public questions

Easy
20 min
code
Public
AI-resistant
C
Arrays
Iteration

Your company is analyzing malware which targets numerical record files.

The malware uses a sliding window over the array of numbers in a file, and tries to match the following pattern:

T, -, -, X, -, -, -, T

Where the position ‘X' is compared to each position 'T'. The window is moved so 'X’ passes through all the values.

The malware has the following rules:

  • If any of the ‘T' positions in the pattern are bigger or equal to 'X’ the malware replaces 'X' with 0.
  • If the 'X' position in the pattern is near the left or right border and is missing a 'T' position neighbor, only the other side is considered.
  • The malware finds all the positions first and only then sets them to 0.

For example, if the values in a record file are the following:

{ 1, 2, 0, 5, 0, 2, 4, 3, 3, 3 }

The expected values after the malware runs are:

{ 1, 0, 0, 5, 0, 0, 0, 3, 3, 0 }

In this example, number 4 was set to 0 because 5 is the bigger number.

Implement the simulate function so that the malware behavior is replicated for further study.

Easy
10 min
code
Public
C
Arithmetic

Implement the function find_roots to find the roots of the quadratic equation: ax2 + bx + c = 0. The function can assign the roots to the values pointed by root1 and root2 in any order. If the equation has only one solution, the function should assign that solution as both roots. The equation will always have at least one solution.

The roots of the quadratic equation can be found with the following formula: A quadratic equation.

For example, find_roots(2, 10, 8) should assign -1,-4 or -4 and -1 to the values pointed by root1 and root2 as the roots of the equation 2x2 + 10x + 8 = 0 are -1 and -4.

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26 more premium C questions

Square, Descriptor, Copy Bit, Shipping, Max Sum, Init Range, Increment, Internal Nodes, Battery, Strings Pointer, Allocate String, Count Letters, Segment, Tiles, Read Write Execute, Weighted Average, Node, Racer, Sort Params, Run in Parallel, Chain Link, Paper Strip, Flimsy Ladder, Circuit Simulator, Calories Burned, Vectors.

Skills and topics tested

  • C
  • Pointers
  • Memory Management
  • Bit Manipulation
  • Arithmetic
  • Algorithmic Thinking
  • Arrays
  • Tree
  • Language
  • Pointer to Pointer
  • Strings
  • 2D Array
  • Pass by Reference
  • Bug Fixing
  • Recursion
  • Multithreading
  • Synchronization
  • Higher Order Function
  • Pthreads
  • Linked List
  • Iteration
  • Conditions

For job roles

  • Back-End Developer
  • C Developer

Sample candidate report

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