第一题：
/****** 例一 *******/
#include<iostream> #include<iomanip> using namespace std; int main() { bool flag = true; cout<<flag<<endl; cout<<boolalpha<<flag<<endl; cout<<flag + 5<<endl; flag = 0; cout<<"执行语句flag=0;后flag的值为:"<<boolalpha<<flag<<endl; flag = 0.0; cout<<"执行语句flag=0.0;后flag的值为:"<<boolalpha<<flag<<endl; return 0; }
/****** 例二 *******/#include<iostream> using namespace std; int main() { int a,b,c,d; a = 4; b = a; a = 5; c = d = 6; c *= a; d %= a + b; cout<<"a = "<<a<<endl <<"b = "<<b<<endl <<"c = "<<c<<endl <<"d = "<<d<<endl; return 0; }
/****** 例三 *******/#include<iostream> using namespace std; int main() { int i,j,m,n; i = 1000; j = 1000; m = i + j; n = i * j; cout<<"m = "<<m<<endl; cout<<"n = "<<n<<endl; return 0; }
/****** 例四 *******/#include<iostream> using namespace std; int main() { int i = 6,j,k,temp; j = ++i; k = i++; ++i = 1; cout<<"i = "<<i<<endl <<"j = "<<i<<endl <<"k = "<<k<<endl; return 0; } /****** 例五 *******/
#include<iostream> using namespace std; int main() { char ch; cout<<"please input a character: "; cin>>ch; ch = ch>= 'a'&&ch<= 'z'?ch - 'a' + 'A': ch; cout <<"The result is: "<<ch<<endl; return 0; } /****** 例六 *******/
#include<iostream> using namespace std; int main() { char ch = 'c'; int a,b = 13; float x,y; x = y = 2.0; a = ch + 5; x = b / 2 / x; y = b / y / 2; cout<<"a = "<<a<<endl <<"x = "<<x<<endl <<"y = "<<y<<endl; return 0; }
/****** 例七 *******/#include<iostream> using namespace std; int main() { int ab,ac; double b = 3.14; char c = 'A'; ab = int(b); ac = int(c); cout<<"b = "<<b<<endl <<"ab = "<<ab<<endl <<"c = "<<c<<endl <<"ac = "<<ac<<endl; return 0; }
第二题：/****** 计算三角形的面积和周长 *******/#include<iostream> #include<math.h> //后面需要使用sqrt()函数计算面积,所以先调用出来 using namespace std; int main() { float a,b,c,d,C,S; //定义三角形三边a,b,c以及d,C,S cout<<"请输入三角形的三边长度"<<endl; cin>>a>>b>>c; if(a+b>c&&a+c>b&&b+c>a) { d=(a+b+c)/2; C=a+b+c; S=sqrt(d*(d-a)*(d-b)*(d-c)); cout<<"该三角形的周长为:"<<C<<endl; cout<<"该三角形的面积为:"<<S<<endl; } else { cout<<"您所输入的三条边的长度无法组成三角形,重新运行程序"<<endl; } return 0; } 第三题：
/******习题三A*****/ #include <iostream> #include <math.h> //数学函数调用头文件<math.h> using namespace std; int main() { int e = 1, f = 4, g = 2; float m = 10.5, n = 4.0, k; k = (e+f)/g+sqrt((double)n)*1.2/g+m; //n的类型强制转换为doubhle型 cout<<"k = "<<k<<endl; return 0; }
/******习题三B******/ #include <iostream> using namespace std; int main() { float x = 2.5, y = 4.7; int a = 7; cout<<x+a%3*(int(x+y)%2)/4<<endl; //(x+y)强制转换成int类型 return 0; }
第四题：
#include <iostream> #include <math.h> //数学函数调用 using namespace std; int main() { float a, b, c; //定义变量a，b，c double x1, x2, k; cout<<"请输入二次项系数: "<<endl; cin>>a; cout<<"请输入一次项系数: "<<endl; cin>>b; cout<<"请输入常数项: "<<endl; cin>>c; 第五题：
/******加密与解密程序******/ #include <iostream> using namespace std; int main() { char a[25],b[25],c[25],e[25]; //定义四个一维字符型数量组 int k; cout<<"欢迎进行名字加密与解密程序"<<endl; //加密解密选择 cout<<"加密请输入“1”，解密请输入任意数字"<<endl; cin>>k; if(k==1) //加密 { int i; cout<<"请输入你要加密的名字"<<endl; //输入要加密的名字 fflush(stdin); //清除输入缓存 cin>>a; //从键盘获取字符 cout<<"该名字的加密成果为："<<endl; //加密结果输出 for(i=0;i<25;i++) { if(a[i]==0) { break; } b[i]=a[i]; b[i]=b[i]+10; //加密方法 c[i]=b[i]; cout<<c[i]; } cout<<endl; } else //解密 { cout<<"请输入你要解密的名字"<<endl; //输入要解密的名字 fflush(stdin); //清除输入缓存 cin>>a; cout<<"该名字的解密成果为："<<endl; //解密结果输出 for(int i=0;i<25;i++) { if(a[i]==0) { break; } b[i]=a[i]; b[i]=b[i]-10; //解密方法 e[i]=b[i]; cout<<e[i]; } cout<<endl; } return 0; }
k = b*b-4*a*c; //用一元二次方程的求根公式求出解x1, x2 x1 = (-b+sqrt(k))/(2*a); x2 = (-b-sqrt(k))/(2*a); if(k>=0) //根据k的值不同分类讨论 { if(x1==x2) { cout<<"一元二次方程的解只有1个，x= "<<x1<<endl; } else { cout<<"一元二次方程的解有2个，x1= "<<x1 <<" x2= "<<x2<<endl; } } else { cout<<"一元二次方程有虚根，x1=i* "<<x1 //求出一元二次方程的虚根 <<" x2=i* "<<x2<<endl; } return 0; }
（这题其实是看我们学霸的，但还是不会
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