第 1 页 共 1 3 页 第三章 1.编写一个求方程ax2 + bx + c = 0的根 的程序，用3个函数分别求当b2-4ac大于零、等于零、和小于零时的方程的根。要求从主函数输入 a,b,c的值并输出结果。 #include < iostream.h > #include < math.h > void equation_1 (int a, int b, int c) { double x1, x2, temp; temp = b*b - 4 * a * c; x1 = (-b + sqrt(temp) ) / (2 * a * 1.0); x2 = (-b - sqrt(temp) ) / (2 * a * 1.0); cout<<"两个不相等的实根"<< endl; cout<<"x1 = "<< x1<<", x2 = "<< x2<< endl; } void equation_2 (int a, int b, int c) { double x1, x2, temp; temp = b*b - 4 * a * c; x1 = (-b + sqrt(temp) ) / (2 * a * 1.0); x2 = x1; cout<<"两个相等的实根"<< endl; cout<<"x1 = "<< x1<<", x2 = "<< x2<< endl; } void equation_3 (int a, int b, int c) { double temp, real1, real2, image1, image2; temp = - (b*b - 4 * a * c); real1 = -b / (2 * a *1.0); real2 = real1; image1 = sqrt(temp); image2 = - image1; cout<<"两个虚根"<< endl; cout<<"x1 = "<< real1<<" + "<< image1<<"j"<< endl; cout<<"x2 = "<< real2<<" + "<< image2<<"j"<< endl; } void main() { int a, b, c; double temp; cout<<"输入 a,b,c的值"<< endl; cin>>a>>b>>c; cout<<"方程为："<< a<<"x*x+"<< b<<"x+"<< c<<" = 0"<< endl; temp = b*b - 4 * a * c; if(temp > 0) equation_1 (a, b, c); if(temp == 0) equation_2 (a, b, c); if(temp < 0) equation_3 (a, b, c); } 2.定义函数up(ch)，如字符变量 ch是小写字母就转换成大写字母并通过 up返回，否则字符 ch不改变。要求在短小而完全的程序中显示这个程序是怎样被调用的。 #include < iostream > using namespace std; char up (char c) { if(c >= 97 && c <= 122) return (c - 32) ; else return c; } void main() { int i; char c[15] = {'A','v','e','t','E','T','%','&','4','Y','e','i','@','9','^'}; for(i = 0 ; i < 15 ; i++) cout<< up(c[i])<<", "; cout<< endl; } 3....
