Question

c语言：输入俩个复数的实部与虚部，计算俩个复数之积，求解为何错了？声明怎么声明？

#include<stdio.h>
float result_real,result_imag;
int main(void)
{
float imag1,imag2,real1,real2;
printf("enter 1st complex number(real and imaginary):");
scanf("%f%f",&real1,&imag1);
printf("enter 2nd complex number(real and imaginary):");
scanf("%f%f",&real2,&imag2);
printf("product of complex is %f+%fi\n",result_real,result_imag);
return 0;
}

void complex_prod(float x1,y1,x2,y2);
{
float result_real,result_imag;
result_real=x1*x2-y1*y2);
result_imag=x1*y2+x2*y1;
return result_real,result_imag;
}

Answer 1

#include<stdio.h>
float result_real,result_imag;
void complex_prod(float x1, float y1,float x2,float y2) ; //声明函数
int main(void)
{
	float imag1,imag2,real1,real2;
	printf("enter 1st complex number(real and imaginary):");
	scanf("%f%f",&real1,&imag1);
	printf("enter 2nd complex number(real and imaginary):");
	scanf("%f%f",&real2,&imag2);
	
	complex_prod(real1,imag1,real2,imag2); //调用函数
	printf("product of complex is %f+%fi\n",result_real,result_imag);
	return 0;
}

void complex_prod(float x1, float y1,float x2,float y2)//这里多了分号，参数定义错
{
	//float result_real,result_imag; 不要了，用全局变量
	result_real=x1*x2-y1*y2; //
	result_imag=x1*y2+x2*y1;
	//return result_real,result_imag; 用不到
}

Answer 2

#include <stdio.h>

float result_real,result_imag;

void complex_prod(float x1,float y1,float x2,float y2) {
//	float result_real,result_imag;
	result_real = x1*x2 - y1*y2;
	result_imag = x1*y2 + x2*y1;
//	return result_real,result_imag;
}

int main(void) {
	float imag1,imag2,real1,real2;
	printf("enter 1st complex number(real and imaginary):");
	scanf("%f%f",&real1,&imag1);
	printf("enter 2nd complex number(real and imaginary):");
	scanf("%f%f",&real2,&imag2);
	complex_prod(real1,imag1,real2,imag2); // 调用函数后，才能使全局变量得到计算结果
	printf("product of complex is %f+%fi\n",result_real,result_imag);
	return 0;
}

Answer 3

#include<stdio.h>
float result_real,result_imag;
int main(void)
{
 float imag1,imag2,real1,real2;
 printf("enter 1st complex number(real and imaginary):");
 scanf("%f%f",&real1,&imag1);
 printf("enter 2nd complex number(real and imaginary):");
 scanf("%f%f",&real2,&imag2);
 printf("product of complex is %f+%fi\n",result_real,result_imag);/*complex_prod函数没有调用result_real,result_imag还没有值 而且还要在调用前声明一下*/
 return 0;
}

void complex_prod(float x1,y1,x2,y2);/*函数参数不能这样定义*/
{
 float result_real,result_imag;
 result_real=x1*x2-y1*y2);
 result_imag=x1*y2+x2*y1;
 return result_real,result_imag;/*定义的函数返回值为空 这里就不能加返回值*/
}