C++ Handbook

`float` — C Keyword

`float` — C Keyword

The float keyword in C: a single-precision IEEE 754 floating-point type.

How to use this reference page

Use reference pages to confirm names, categories, nearby facilities, and the constraints that matter before writing or reviewing code.

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float (C)

A single-precision floating-point type (IEEE 754 binary32, 32 bits), providing approximately 7 significant decimal digits.

Syntax

float f;
float f = 3.14f;    /* 'f' suffix for float literal */

Example

#include <stdio.h>
#include <math.h>

int main(void) {
    float r = 5.0f;
    float area = 3.14159f * r * r;

    printf("%.4f\n", area);   /* 78.5397 */

    /* Precision limits */
    float x = 0.1f + 0.2f;
    printf("%.10f\n", x);     /* not exactly 0.3 */
    return 0;
}

Notes

Example in practice

int main() {
    // Pick one facility from this reference page.
    // Write the smallest program that exercises its main precondition,
    // complexity rule, or lifetime constraint before scaling up.
    return 0;
}