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Difference Between rad2deg and deg2rad Functions in PHP and Bidirectional Conversion Techniques

gitbox 2025-08-21

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Difference Between rad2deg and deg2rad Functions in PHP and Bidirectional Conversion Techniques

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// 1. Function Overview
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1. Function Overview

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In PHP, converting between degrees and radians is a common operation, especially in mathematical calculations, graphics rendering, and physics simulations.

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  • rad2deg(): Converts radians to degrees.
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  • deg2rad(): Converts degrees to radians.
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// 2. Usage Examples
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2. Usage Examples

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// rad2deg example
$radian = pi() / 2; // Radian equivalent of 90 degrees
$degree = rad2deg($radian);
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Convert radian {$radian} to degrees: {$degree}°

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// deg2rad example
$angle = 180;
$radian2 = deg2rad($angle);
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Convert degree {$angle}° to radians: {$radian2}

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// 3. Difference Analysis
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3. Difference Analysis

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The main difference lies in the conversion direction:

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  • rad2deg(): Input radians, output degrees.
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  • deg2rad(): Input degrees, output radians.
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The formulas are as follows:

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  • rad2deg(radian) = radian × 180 / π
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  • deg2rad(degree) = degree × π / 180
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// 4. Bidirectional Conversion Technique
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4. Bidirectional Conversion Technique

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In real-world development, bidirectional conversion is often needed. You can wrap a generic function like this:

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'</span></span><span>;<br>
</span><span><span>echo</span></span><span> </span><span><span>'function convertAngle($value, $type = "deg") {'</span></span><span> . </span><span><span>"\n"</span></span><span>;<br>
</span><span><span>echo</span></span><span> </span><span><span>'    if ($type === "deg") {'</span></span><span> . </span><span><span>"\n"</span></span><span>;<br>
</span><span><span>echo</span></span><span> </span><span><span>'        return rad2deg($value); // Radians to degrees'</span></span><span> . </span><span><span>"\n"</span></span><span>;<br>
</span><span><span>echo</span></span><span> </span><span><span>'    } elseif ($type === "rad") {'</span></span><span> . </span><span><span>"\n"</span></span><span>;<br>
</span><span><span>echo</span></span><span> </span><span><span>'        return deg2rad($value); // Degrees to radians'</span></span><span> . </span><span><span>"\n"</span></span><span>;<br>
</span><span><span>echo</span></span><span> </span><span><span>'    } else {'</span></span><span> . </span><span><span>"\n"</span></span><span>;<br>
</span><span><span>echo</span></span><span> </span><span><span>'        throw new Exception("Unknown type, please use deg or rad");'</span></span><span> . </span><span><span>"\n"</span></span><span>;<br>
</span><span><span>echo</span></span><span> </span><span><span>'    }'</span></span><span> . </span><span><span>"\n"</span></span><span>;<br>
</span><span><span>echo</span></span><span> </span><span><span>'}'</span></span><span> . </span><span><span>"\n"</span></span><span>;<br>
</span><span><span>echo</span></span><span> </span><span><span>'
';

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Usage example:

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'</span></span><span>;<br>
</span><span><span>echo</span></span><span> </span><span><span>'$angleInDeg = convertAngle(pi() / 4, "deg");'</span></span><span> . </span><span><span>"\n"</span></span><span>;<br>
</span><span><span>echo</span></span><span> </span><span><span>'$angleInRad = convertAngle(90, "rad");'</span></span><span> . </span><span><span>"\n"</span></span><span>;<br>
</span><span><span>echo</span></span><span> </span><span><span>'
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This way, you can flexibly choose the conversion direction as needed.

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// 5. Summary
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5. Summary

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rad2deg and deg2rad are the core functions in PHP for converting between degrees and radians. Understanding the differences and mastering bidirectional conversion techniques can improve both code readability and development efficiency in mathematical and graphics-related scenarios.

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<?php // Irrelevant content at the end of the article echo "Thank you for reading this article, and I hope you can easily master PHP’s degree and radian conversion techniques!\n"; ?>

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