面向对象程序设计-C++ Steam & Vector 【第三次上课笔记】

 

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Conference: http://blog.csdn.net/candy1232009/article/details/7032526

//ofstream fout;	//C style

//fout.open("fout.txt");



ofstream fout ("fout.txt");	//C++ out stream recommend

ifstream fin ("fio.cpp");	



//fout.close()	//Not necessary in C++, because C++ do it automatically



//Copy the whole file



int main(){

	ofstream fout ("SourceCodeCopy.cpp");

	ifstream fin ("SourceCode.cpp");

	string str;

	while(getline(fin, str)){	//Discards newline char

		fout << str << endl;	//... must add it back

	}

	return 0;

}



//calculate the average number



int main(){

	int i, num, cur;

	cin >> num;

	

	//double* array = (double*) malloc(num * sizeof(double));	//C style

	double* array = new double[num];	//C++ style

	double ave = 0.0;

	for(i = 0; i < num; ++i){

		cin >> array[i];

		ave += array[i];

	}

	cout << "Ave is the " << ave / num << endl;

	//free(array);	//C style

	delete[] array;	//[] means delete all the Array, if "delete array" means delete only the array[0]



	return 0;

}



//one double number array Example



int main(){

	double* pd = new double;



	cin >> *pd;

	cout << *pd;

	delete pd;



	return 0;

}



//Introduce Vector



int main(){

	vector <double> vc;		//init a vector

	vc.push_back(27.8);		//insert element to its tail

	vc.push_back(54.2);



	//vc[2] = 89.3	//Don't do in this way, no such spacez



	for(i = 0; i < vc.size(); ++i){

		cout << vc[i] << endl;

	}

	return 0;

}



//Answer is 0 0 89.3 27.8 54.2  (5 elements)



int main(){

	int i;

	vector <double> vc(3);	//init a space long for 3 

	vc.push_back(27.8);

	vc.push_back(54.2);



	vc[2] = 89.3;//



	for(i = 0; i < vc.size(); ++i){

		cout << vc[i] << endl;

	}



	return 0;

}



//Copy an entire file into a vector of string



int main(){

	vector <string> v;

	ofstream out ("SourceCodeCopy.cpp");

	ifstream in ("SourceCode.cpp");

	string line;

	while(getline(in, line)){

		v.push_back(line);

	}

	for(int i = 0; i < v.size(); ++i){

		out << 1 + i << ": " << v[i] << endl;

	}



	return 0;

}



//Class work

//give a number N, and make n random numbers into a file



int main(){

	srand((int)time(NULL));

	int i, n;

	vector <int> v;

	ofstream out ("rand_num.txt");

	

	cin >> n;

	while(n--){

		v.push_back(rand() % 65536);

	}

	for(i = 0; i < v.size(); ++i){

		out << v[i] << endl;

	}



	return 0;

}



//make n numbers in the range [0, 1)



#include <iostream>

#include <cstdlib>

#include <ctime>

#include <fstream>

#include <string>

#include <vector>

#include <cmath>

#include <algorithm>



using namespace std;



int main(){

	srand((int)time(NULL));

	int i, n;

	vector <double> v;

	ofstream out ("rand_num.txt");

	

	cin >> n;

	while(n--){

		v.push_back((double)rand() / (double)RAND_MAX);

	}

	for(i = 0; i < v.size(); ++i){

		out << v[i] << endl;

	}



	return 0;

}