91 lines
1.5 KiB
C
91 lines
1.5 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#define WEIGHT 3.0e-23
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#define KQ 950
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static void water(void)
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{
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float num;
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float sum;
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printf("Please input for num:");
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scanf("%f", &num);
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if (num <= 0)
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{
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fprintf(stderr, "Input Error!\n");
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exit(1);
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}
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sum = num * KQ / WEIGHT;
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printf("Total = %e\n", sum);
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return;
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}
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static void area(void)
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{
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float a, b, c;
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float s, area;
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printf("Please input:");
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scanf("%f%f%f", &a, &b, &c);
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// 对scanf做好校验是好习惯
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if (a + b <= c || b + c <= a || a + c <= b)
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{
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fprintf(stderr, "EINVAL!\n");
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exit(0);
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}
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printf("a = %f\n", a);
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printf("b = %f\n", b);
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printf("c = %f\n", c);
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// s = 1 / 2 * (a + b + c);
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s = 1.0 / 2 * (a + b + c);
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printf("s = %f\n", s);
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// s=0.000000
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// 1 / 2是int型计算，得到的是商0余1
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area = sqrt(s * (s - a) * (s - b) * (s - c));
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printf("area = %f\n", area);
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}
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void root(void)
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{
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float a, b, c;
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float disc;
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float p, q;
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float x1, x2;
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printf("Please input :\n");
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scanf("%f%f%f", &a, &b, &c);
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if (b * b - 4 * a * c < 0)
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{
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fprintf(stderr, "EINVAL\n");
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exit(1);
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}
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disc = b * b - 4 * a * c;
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p = -b / 2 * a;
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q = sqrt(disc) / 2 * a;
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x1 = p + q;
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x2 = p - q;
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printf("x1 = %f\n", x1);
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printf("x2 = %f\n", x2);
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}
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int main()
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{
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// water();
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// area();
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root();
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exit(0);
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} |