Question

当我尝试在输出文件上写字时，会发生一件奇怪的事情：

 int main(int argc, char* argv[])
 {


  std::string outputFile = "fitness.out";
  ofstream output( outputFile.c_str() );


  FitnessFactory fitnessFactory;

  //if i write on file here it's ok

  vector<string> params;
  params[0]= 10;
  params[1]=120;

  //if i write on file here not ok, file empty

  Strategy* strategy = fitnessFactory.getStrategy("OneMax", params);
  vector<string> individual;


for(unsigned i = 0; i < argc-1; i++){

string inputFile = argv[i+1];
ifstream input( inputFile.c_str() );
while( input.good() )
{
    string temp;
    input>>temp;
    individual.push_back(temp);
}
input.close();
// if i write on file, before call strategy->evaluate,for example
// output << "hello"<<endl;
// file contains "hello"
string res = strategy->evaluate(individual);
//if i write here file is empty
//output<< res << endl;
}

其他cpp文件是：

factoryMethod.cpp

      #include <stdio.h>
#include "strategy.cpp"
using namespace std;
class factoryMethod
{

public:
     virtual Strategy* getStrategy(string x, vector<string> params)    = 0;


};

 Strategy* factoryMethod :: getStrategy(string x, vector<string>  
 params)
{
}


class FitnessFactory : public factoryMethod
{
public:
      Strategy* getStrategy(string x, vector<string> params) {

        Strategy* s;

          if(x=="OneMax")
          s = new OneMax();
          else if (x=="Weierstrass") s = new Weiestrass();
          return s;
      }
};

strategy.cpp

std::string Convert (float number){
std::ostringstream buff;
buff<<number;
return buff.str();
}

class Strategy
{
 public:
     virtual string evaluate(vector<string> v) = 0;
     virtual void strategy(vector<string> params);
 public: vector<string> fparams;
 };

string Strategy :: evaluate(vector<string> v)
{

}

void Strategy :: strategy(vector<string> v){
fparams = v;
}

class OneMax : public Strategy
{
public:
      string evaluate(vector<string> v) {
          string x = v[0];
         int count = 0;
 for (int i = 0; i < x.size(); i++)
        if (x[i] == '1') count = count + 1;

            string ret = static_cast<ostringstream*>( &   
(ostringstream() << count) )->str();
            return ret;
      }
};
class Weiestrass: public Strategy
{
public:
     string evaluate(vector<string> v) {
  //   int repetitions = atoi( fparams[0].c_str() );
 //  int iterations = atoi( fparams[1].c_str() );
int repetitions = 10;
int iterations = 120;
vector<float> x;
for(int i = 0; i < v.size(); i++){
    float temp = ::atof(v[i].c_str());
    x[i] = temp;
}
float fRes=0, fSum, b=2, h=0.5;

for (int j = 0; j < repetitions; j++)
{

        fRes = 0;
        for (int i = 0; i < x.size(); i++)
    {
            fSum=0;
            for (int k = 0; k < iterations; k++) fSum += pow(b,-    
(float)k*h) * sin(pow(b,(float)k)*x[i]);
            fRes += abs(fSum);
        }
}

string s = Convert(fRes);
return s;
}
};

因此，当我在调用评估文件后尝试写入函数的结果或任何其他值时，该文件为空。我不明白为什么?? !!

Answer 1

vector<string> params;
params[0]= 10;
params[1]=120;

没有。 std::vector::operator[]()不会增加内部元素的数量。 vector<string> params(2);可以在构造中创建2个元素，params.resize(2)可以在分配之前创建2个元素，或者

params.push_back("10");
params.push_back("120");

没有写出输出文件c ++

1 个答案: