c++重要程序

设定输出小数位数
cout<<setiosflags(ios::fixed)<<setprecision(7);
冒泡法排序
int i,j,k;
for(i=0;i<N;i++)
{for(j=0;j<N-1-i;j++)
if(A[j+1]>A[j])
{k=A[j+1];
A[j+1]=A[j];
A[j]=k;}
两个有序数组合并为一个有序数组
int i=0,j=0,k=0;
while(i<m&&j<n)
{if(e[i]<a[j])
{s[k++]=e[i++];}
else if(e[i]==a[j])
{s[k++]=e[i];
i++;
j++;}
else
{s[k++]=a[j++];}
}
while(i<m)
s[k++]=e[i++];
while(j<n)
s[k++]=a[j++];
十进制数转化为二进制
int j,i=0;
char temp;
while (n!=0)
{
des[i] = n%2+'0';
n = n/2;
i++;
}//转化结果为2进制最高位在des的下标最低处，顺序刚好反了des[i] = NULL;
for (j=0;j<i/2;j++)//将顺序倒过来
{
temp = des[j];//交换
des[j] = des[i-1-j];
des[i-1-j] = temp;
}
二分法
#include <iostream> using namespace std; int main() { int high=9,low=0,m,k; int a[10]={1,2,3,4,5,6,7,8,9,10}; cin>>k; while (high>=low) { m=(high + low)/2; if(k<a[m]) high=m-1; else if(k>a[m]) low=m+1; else break; } if (k!=a[m])cout<<"ERROR.The element is not found"<<endl; else cout<<"The element is found. It in the position of "<<m+1<<endl; return 0; }
C++选择排序： #include<iostream> using namespace std; int main()
{ int num[10] = {9,8,10,3,4,6,4,7,2,1};
int m;
cout<<"排序前："<<endl; for (m=0;m<10;m++) {
cout<<num[m]<<" "; }
for (int i=0;i < 10;i++) { int pos = i;
for (int j=i;j< 10;j++) { if (num[pos] > num[j]) {
pos =j; } }
int tem;
tem = num[pos]; num[pos] = num[i]; num[i] = tem; }
cout<<endl<<"排序后："<<endl;
for (int m = 0;m<10;m++) {
cout<<num[m]<<" "; }
system("PAUSE"); return 0;
}
最大公约数和最小公倍数
#include<iostream>
#include<cmath>
using namespace std;
int main()
{
int m,n,a,b,r;
cin>>m>>n;
if(m>n)
{a=m;b=n;}
else
{a=n;b=m;}
r=m%n;
while(r!=0)
{r=a%b;
a=b;
b=r;
}
cout<<a<<endl;
cout<<m*n/a<<endl;
}
求定积分
#include <iostream>
#include <iomanip>
#include<cmath>
using namespace std;
int main()
{
double f(double);
double a,b,x,sum=0;
int n;
cout<<"Please input a , b , n："<<endl;
cin>>a>>b>>n;
for(double i=a;i<=b;i+=1.0/n)
{
x=i;
sum=sum+f(x)/n;
}
cout<<setiosflags(ios::fixed)<<setprecision(6)<<sum<<endl;
return 0;
}
double f(double x)
{
double y;
y=sin(x);
return y;
}。