Operators

Last reviewed May 28, 2026 Content v20260528

Track mode: server_compiled
Means: Compiled runner
Reading: ~1 min
Level: beginner

This lesson

This lesson teaches Operators: the syntax, patterns, and safety habits you need before advancing in C.

Teams still ship Operators in C codebases—skipping it leaves gaps in debugging and code reviews.

You will apply Operators in contexts like: Kernels, drivers, embedded devices, and performance libraries used by other languages.

Write C in main.c with int main(), click Run on server—the dev runner compiles with cc/gcc -std=c11 and runs the binary; read stderr for compile and linker errors (LEARNING_RUNNER_ENABLED=true).

When you can explain the previous lesson's ideas without copying starter code.

C operators will feel familiar from Java: arithmetic, comparison, logical, and assignment. Watch integer division and operator precedence.

Arithmetic and assignment

int a = 7, b = 3;
int sum = a + b;      /* 10 */
int quot = a / b;     /* 2 — integer division truncates */
double exact = 7.0 / 3.0;

Increment and compound assignment

++i and i++ differ when their value is used in an expression. Prefer simple, readable forms while learning.

Logical operators

&&, ||, and ! return 0 or 1. C has no distinct boolean type unless you include stdbool.h.

Important interview questions and answers

Q: Result of 5 / 2 in C?
A: 2 with integer operands—use floating literals for fractional results.
Q: Difference between = and ==?
A: = assigns; == compares. Accidental assignment in conditions is a classic bug.

Self-check

What is 9 % 4?
Does 3.0 / 2 produce an integer?

Interview prep

Integer division trap?: 7 / 3 is 2, not 2.333—cast to double or use floating literals for fractional math.

Interview tip Lesson completion confidence

Can you explain this lesson in 30 seconds without reading notes?

Self-reflection (saved on this device)

Not saved yet.

Playground

Runs on the configured server runner (dev: npm run runner with LEARNING_RUNNER_ENABLED=true). Output appears below the editor.

Code runner not available

Server runner is disabled. Set LEARNING_RUNNER_ENABLED=true and LEARNING_RUNNER_URL in .env (see .env.example).

Check yourself

Multiple choice — immediate feedback.

Discussion

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Starter discussion topics

++i vs i++?
Integer overflow UB?

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