C++ Academy · Lesson

Integer vs Floating Point Types

Pick the right numeric type by understanding sizes, ranges, and precision trade-offs.

Lesson 1 of 413 steps

Integer vs Floating Point Types is a free C++ Academy lesson on CoddyKit. This is lesson 1 of 4. Any 3 lessons of this learning path are free to read in full — after that, CoddyKit PRO unlocks every lesson, plus hands-on practice with a built-in code editor and a 24/7 AI tutor. It is part of the C++ Academy learning path, and your progress syncs across the web and the CoddyKit app. The C++ Academy course includes 4 lessons in total.

Two Number Worlds

C++ has two families of numeric types: integers (no fractions, exact) and floating point (approximate, with fractions). Pick the right family for the job.

Integer Types

Built-in integer types and typical sizes on 64-bit systems:

char — 1 byte
short — 2 bytes
int — 4 bytes
long — 4 or 8 bytes
long long — 8 bytes

Signed vs Unsigned

Add unsigned to drop the negative range. Unsigned arithmetic wraps around modulo 2^N — sometimes useful, often a footgun.

unsigned int u = 0;
u -= 1;  // wraps around to 4,294,967,295

Fixed-Width Integers

Use the types in <cstdint> when you need exact sizes — for protocols, file formats, or platform portability.

#include <cstdint>
int8_t   tiny  = 100;
int32_t  word  = 100000;
int64_t  big   = 1LL << 40;
uint64_t huge  = 18446744073709551615ULL;

Floating Point Types

Three floating types of increasing precision:

float — 32-bit, about 7 decimal digits
double — 64-bit, about 15 decimal digits
long double — typically 80 or 128 bits

IEEE 754 Format

Floats follow the IEEE 754 standard: sign, exponent, mantissa. They can represent very large and very small values, but not exactly.

Floating Point Pitfalls

Most decimal numbers cannot be represented exactly in binary. 0.1 + 0.2 is not exactly 0.3.

double sum = 0.1 + 0.2;
std::cout << (sum == 0.3);   // false on most systems
std::cout << sum;            // 0.3 but printed approximately

Comparing Floats Safely

Never compare floats with ==. Compare within a small tolerance (epsilon).

bool approxEqual(double a, double b, double eps = 1e-9) {
    return std::abs(a - b) < eps;
}

Special Float Values

Floats have three special values: NaN (not a number), +inf, and -inf. Use the predicates in <cmath> to check for them.

#include <cmath>
double x = std::sqrt(-1.0);
if (std::isnan(x)) std::cout << "Not a number";
if (std::isinf(x)) std::cout << "Infinity";

When to Use Each

Choose by domain:

Counts and indices → int or size_t
Scientific or graphical math → double
Money → never double! Use scaled integers (cents) or a decimal library

Type Sizes vary by Platform

Standard guarantees only minimum sizes. int may be 16, 32, or 64 bits. For portability use <cstdint> fixed-width types in data structures.

Quick Check

Which type should you use to represent monetary values precisely?

Answer it in the interactive lesson

Recap

Integers are exact; floats are approximate. Pick int or fixed-width integers for counts, double for scientific math, and never use floats for money. Compare floats with a tolerance, never ==.

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Frequently Asked Questions

Is the “Integer vs Floating Point Types” lesson free?

Yes — any 3 lessons of the C++ Academy learning path, including “Integer vs Floating Point Types”, are free to read in full here on the web. After that, CoddyKit PRO unlocks every lesson, plus interactive practice with a built-in code editor and a 24/7 AI tutor. The C++ Academy course includes 4 lessons in total.

What will I learn in “Integer vs Floating Point Types”?

Pick the right numeric type by understanding sizes, ranges, and precision trade-offs. You practise C++ Academy with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.

Do I need any experience to start C++ Academy?

No prior experience is required. C++ Academy on CoddyKit is structured for beginners through advanced learners, so you can start here or from the beginning and move at your own pace. This is lesson 1 of 4.

How long does the “Integer vs Floating Point Types” lesson take?

Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.

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