Scalar Data Types

The last section focused on how variables are declared. This one shifts to the values that those variables hold.

For early scpp programs, four scalar types cover a lot of ground:

• int for whole numbers,
• double for decimal values,
• bool for true-or-false decisions,
• char for one character at a time.

As before, save each short example as concepts.scpp, then build and run it:

scpp concepts.scpp -o concepts
./concepts

Whole numbers and decimal numbers

int is the usual starting point for counting, indexing, and other whole-number work. double is the common choice when fractions matter.

import std;

int main() {
    int left = 10 - 3;
    double price = 1.25 + 0.5;

    std::println("left = {}, price = {}", left, price);
    return 0;
}

Output:

left = 7, price = 1.75

Keep those calculations in their own types. The int expression stays entirely integer-based, and the double expression stays entirely floating-point.

If you later need an exact width instead of the friendly int / double spellings, scpp also provides names such as int32_t, uint64_t, and float64_t.

bool is for real conditions

Conditions in scpp should already be bool. A comparison gives you that bool directly.

import std;

int main() {
    int lives = 3;
    bool keep_playing = lives > 0;

    if (keep_playing) {
        std::println("keep playing");
        return 0;
    }

    std::println("game over");
    return 0;
}

Output:

keep playing

That is a small but important difference from ordinary C++. scpp does not ask you to treat arbitrary integers as “truthy” or “falsey”. Instead, write a real comparison such as lives > 0 and keep the result in a bool.

char holds one character

Use char when one byte-sized character value is enough.

import std;

int main() {
    char grade = 'A';

    std::println("grade = {}", grade);
    return 0;
}

Output:

grade = A

Single quotes matter here. 'A' is one char; "A" would be text, not a single character value.

One more rule to remember

scpp keeps scalar types separate. bool, char, int, and double do not silently convert into one another. That is why the examples above keep each expression within one scalar type and use comparisons when a bool is needed.

This may feel stricter at first, but it makes the type of every calculation more obvious at a glance.

The next section will keep building on these basics by packaging calculations and actions into named functions.

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