C语言程序设计教程（第三版）课后习题8.2 （C语言代码）

解题思路:





注意事项:





参考代码:

#include <stdio.h>

#include <math.h>

#define MIN_POS   1e-6

#define MAX_NEG   (-1e-6)

//μ± b*b-4*a*c > 0ê± 

void root_real(float a,float b,float c)

{

float m = -b/(2*a);

float n = b*b-4*a*c;

if(n > MIN_POS)

{

n = sqrt(n)/(2*a);

printf("x1=%.3f\n",m+n);

printf("x2=%.3f\n",m-n);

}

} 

//μ± b*b-4*a*c == 0ê± 

void root_zero(float a,float b,float c)

{

float m = -b/(2*a);

float n = b*b-4*a*c;

if((n < MIN_POS)&&(n > MAX_NEG))

{

printf("x1=%.3f\n",m);

printf("x2=%.3f\n",m);

}

} 

//μ± b*b-4*a*c < 0ê± 

void root_image(float a,float b,float c)

{

float m = -b/(2*a);

float n = b*b-4*a*c;

if(n < MAX_NEG)

{

n = sqrt(-n)/(2*a);;

printf("x1=%.3f+%.3fi\n",m,n);

printf("x2=%.3f-%.3fi\n",m,n);

}

} 

int main(void)

{

float a;

float b;

float c;

if((scanf("%f%f%f",&a,&b,&c) == 3)&&((a > MIN_POS)||(a < MAX_NEG)))

{

root_real(a,b,c);

  root_zero(a,b,c);

  root_image(a,b,c);

}

else

{

printf("the type of input is wrong\n");

printf("please input again!\n");

}

return 0;

}