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41 lines
724 B
41 lines
724 B
#include <stdio.h>
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#include <math.h>
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typedef struct point {
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double x, y;
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} point;
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/*
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Nested the anonymous struct in anonymous union together with a named struct
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to support direct access to 2D point in the 3D point structure.
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*/
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typedef struct {
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union {
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struct point;
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point p2;
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};
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double z;
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} threepoint;
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double length(point p) {
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return sqrt(p.x * p.x + p.y * p.y);
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}
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double threelength(threepoint p) {
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return sqrt(p.x * p.x + p.y * p.y + p.z * p.z);
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}
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int main() {
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threepoint p = {.x = 3, .y = 0, .z = 4};
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printf("p is %g units from the origin\n", threelength(p));
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double xylength = length(p.p2);
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printf("Its projection onto the XY plane is %g units from the origin\n", xylength);
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}
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