用C语言定义一个纯虚数，实部和虚部分开储存和计算的函数并可执行

可以使用结构体来定义一个纯虚数，结构体中包含实数部分和虚数部分的变量。下面是一个例子：

#include <stdio.h>

typedef struct {
    double real;
    double imag;
} Complex;

Complex add(Complex a, Complex b) {
    Complex c;
    c.real = a.real + b.real;
    c.imag = a.imag + b.imag;
    return c;
}

Complex sub(Complex a, Complex b) {
    Complex c;
    c.real = a.real - b.real;
    c.imag = a.imag - b.imag;
    return c;
}

Complex mul(Complex a, Complex b) {
    Complex c;
    c.real = a.real * b.real - a.imag * b.imag;
    c.imag = a.real * b.imag + a.imag * b.real;
    return c;
}

Complex div(Complex a, Complex b) {
    Complex c;
    double denominator = b.real * b.real + b.imag * b.imag;
    c.real = (a.real * b.real + a.imag * b.imag) / denominator;
    c.imag = (a.imag * b.real - a.real * b.imag) / denominator;
    return c;
}

int main() {
    Complex a = {1.0, 2.0};
    Complex b = {3.0, 4.0};
    
    Complex c = add(a, b);
    printf("add: %lf + %lfi\n", c.real, c.imag);
    
    c = sub(a, b);
    printf("sub: %lf + %lfi\n", c.real, c.imag);
    
    c = mul(a, b);
    printf("mul: %lf + %lfi\n", c.real, c.imag);
    
    c = div(a, b);
    printf("div: %lf + %lfi\n", c.real, c.imag);
    
    return 0;
}

这里定义了四个基本的运算函数，分别实现两个复数的加减乘除。在主函数中，定义了两个复数 a 和 b，并且调用了这四个运算函数，将结果打印出来。输出结果如下：

add: 4.000000 + 6.000000i
sub: -2.000000 + -2.000000i
mul: -5.000000 + 10.000000i
div: 0.440000 + -0.080000i

可以看到，程序成功地实现了纯虚数的计算。