我不确定该如何表达我要问的内容；在 C++ 中，使用 stdio.h 标头而不是 iostream，我将如何做到这一点，以便如果在任何时候按下转义键，程序就会终止？有什么我可以在程序顶部添加一次的，还是我必须将它单独添加到每个循环/条件中？下面是我的代码（sleep() 函数仅用于视觉加载/计算效果）：
#include <stdio.h>
#include <math.h>
#include <windows.h>
void repeat();
void quadratic()
{
double a, b, c;
double ans[2];
printf("-Arrange your equation in the form aX^2+bX+c \n-Enter the value of a: ");
scanf("%lf", &a);
printf("-Enter the value of b: ");
scanf("%lf", &b);
printf("-Enter the value of c: ");
scanf("%lf", &c);
double radical=((b*b)-(4*a*c));
double root=sqrt(radical);
double negB=(-1)*b;
double denominator=2*a;
if(denominator==0)
{
printf("Calculating");
Sleep(100);
printf(".");
Sleep(100);
printf(".");
Sleep(100);
printf(".");
Sleep(100);
printf("\nError: Denominator must be non-zero.\n \n \n");
}
else if(radical==0)
{
ans[0]=negB/denominator;
printf("Both roots are equal: both values are X=%lf\n \n \n", ans[0]);
}
else if(radical<0)
{
printf("Calculating");
Sleep(100);
printf(".");
Sleep(100);
printf(".");
Sleep(100);
printf(".");
Sleep(100);
double r,i;
radical*=-1;
r=negB/(2*a);
i=sqrt(radical)/(2*a);
printf("\nBoth roots are imaginary numbers.\n");
printf("Non-real answer(s): X=%lf+%lfi X=%lf-%lfi\n \n \n",r,i,r,i);
}
else
{
ans[0]=(negB+root)/denominator;
ans[1]=(negB-root)/denominator;
printf("Calculating");
Sleep(100);
printf(".");
Sleep(100);
printf(".");
Sleep(100);
printf(".");
Sleep(100);
printf("\nX=%lf, X=%lf\n \n", ans[0], ans[1]);
}
repeat();
}
void repeat()
{
quadratic();
}
int main(void)
{
quadratic();
return 0;
}