c++常见操作的模板
2024-09-07 04:38:58
1.统计时间
#include<ctime>
clock_t startTime = clock();
code();
clock_t endTime = clock();
cout << endl<< "time: " << double(endTime - startTime) / CLOCKS_PER_SEC << " s"<<endl;
2.读取文件
#include<iostream>
#include<fstream>
#include<cstdlib>
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"<<filename<<endl;
cout<<"Program terminating.\n";
exit(EXIT_FAILURE);
}
double value; //1
double sum=0.0;
int count=0;
inFile>>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:"<<count<<endl;
cout<<"sum:"<<sum<<endl;
}
inFile.close();
return 0;
}
3.写入文件
#incluede<fstream>
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<iostream>
#include<cstdlib>
#include<ctime>
using namespace std;
int main()
{
double target;
srand(time(0));
for(int i=0;i<=20;i++)
{
target=rand()%90;
cout<<target<<endl;
}
return 0;
}
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<row;i++)
{
B[i]=new double[col];
}
for(i=0;i<row;i++)
{
for(j=0;j<col;j++)
{
B[i][j]=*(A+i*col+j);
cout<<B[i][j]<<" ";
}
cout<<endl;
}
for(i=0;i<row;i++)
{
delete[] B[i];
}
delete[] B;
}
//调用： show(A[0],4,7);
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