1.统计时间

#include
    
     clock_t startTime = clock();code();clock_t endTime = clock();cout << endl<< "time: " << double(endTime - startTime) / CLOCKS_PER_SEC << " s"<
    

2.读取文件

#include
    
     #include
     
      #include
      
       const int SIZE=60; int main(){    using namespace std;    char filename[SIZE]="information.txt";    ifstream inFile;    inFile.open(filename);    if(!inFile.is_open())    {        cout<<"Could not open the file"<
       
        <
        
         >value;                                                                     //1    while(inFile.good())    {        ++count;        sum=sum+value;        inFile>>value;    }    if(inFile.eof())    cout<<"end of file reached.\n";    else if(inFile.fail())    cout<<"input terminated by data mismatch.\n";    else    cout<<"input terminated for unknown reason.\n";    if(count==0)    cout<<"NO DATA PROCESSED.\n";    else{        cout<<"items read:"<
         
          <
         
        
       
      
     
    

3.写入文件

#incluede
    
     ofstream outFile;outFile.open("carinfa.txt");        //要放入的文件名outFile<<...                        //放入的信息...outFile.close();                    //关闭文件
    

4.产生0~89之间的随机数

#include
    
     #include
     
      #include
      
       using namespace std;int main(){    double target;    srand(time(0));    for(int i=0;i<=20;i++)    {    target=rand()%90;    cout<
       
        <
       
      
     
    

6.传二维数组

int show(double* A,int row,int col){    int i,j;    double** B=new double*[col];    for(i=0;i