Question

这个项目的目的是建立自己的单元测试并使用c-strings。

项目：DNA测序链

以下是重叠时匹配的两条DNA链的示例：

Strand 1: ACGGACATAGTCATT
Strand 2:      CATAGTCATTTCATG
Combined: ACGGACATAGTCATTTCATG

当我尝试实施以下内容时，我感到很茫然：

Strand必须有一个方法Strand substrand(size_t i, size_t j) const，该方法会返回从位置i开始并在位置j - 1结束的链的副本。想想“Python切片。”

更新：我最近回答了自己的问题并更新了void test_substrand()和Strand Strand::substrand(size_t start, size_t end) const。我收到了分段错误。

到目前为止，这是我的代码，其文件名在其正文下方。

void test_substrand()
{
    Strand s1;
    s1.setStrand("Hellow World");
    s1.substrand(1, 4);
    std::cout << "Substrand: " << s1.getStrand() << std::endl;
}

int main()
{
    test_substrand();
    return 0;
}

TEST.CPP

#ifndef _STRAND_H_
#define _STRAND_H_
#include <cstdlib>
#include <string>
#include <string>

class Strand
{
public:
  Strand();
  Strand(const char *src);
  ~Strand();
  Strand & operator=(const Strand &rhs);
  const char *getStrand() const;
  void setStrand(const char *strand);
  Strand & operator+=(const Strand &rhs);
  Strand operator+(const Strand &rhs) const;

  Strand substrand(size_t start, size_t end) const;

protected:
  char *mStrand;
};

#endif /* _STRAND_H_ */
/* Local Variables: */
/* mode:c++         */
/* End:             */

Strand.h

#include "Strand.h"
#include <cstring>
#include <string>

// default constructor
Strand::Strand()
  : mStrand(0)
{
}

// copy constructor
Strand::Strand(const char *src)
  : mStrand(0)
{
  *this = src;
}

// destructor
Strand::~Strand()
{
  if(mStrand != 0)
  {
    delete [] mStrand;
    mStrand = 0;
  }
}

// assignment operator
Strand &Strand::operator=(const Strand &rhs)
{
  setStrand(rhs.mStrand);
  return *this;
}

// Get Strand
const char *Strand::getStrand() const
{
  return mStrand;
}

// Set Strand
void Strand::setStrand(const char *strand)
{
  if(mStrand)
  {
    delete [] mStrand;
    mStrand = 0;
  }
  if(strand)
  {
    mStrand = new char [std::strlen(strand) + 1];
    std::strcpy(mStrand, strand);                 
  }
}

size_t Strand::size() const
{
  return mBases;
}

// operator +=
Strand &Strand::operator+=(const Strand &rhs)
{
  char *new_strand;
  new_strand = new char [std::strlen(mStrand) + std::strlen(rhs.mStrand) + 1];

  strcat(strcpy(new_strand, mStrand), rhs.mStrand); 

  setStrand(new_strand);
  delete [] new_strand;
  return *this;
}

// operator +
Strand Strand::operator+(const Strand &rhs) const
{
  Strand value;
  value = *this;
  value += rhs;
  return value;
}

// substrand "python" slice
Strand Strand::substrand(size_t start, size_t end) const
{
  size_t k, i, size;

  size = end - start;

  char *new_strand;
  new_strand = new char [size +1];
  for (k = start, i = 0; k < end; k++, i++)
  {
    new_strand[i] = mStrand[k];
  }

  new_strand[k] = 0;
  Strand setStrand(new_strand);
  delete [] new_strand;
  new_strand = 0;
  return setStrand;
}

Strand.cpp

Answer 1

固定代码中存在两个问题。

首先，测试函数忽略了substrand的结果，并始终打印原始的strand。这是固定代码：

void test_substrand()
{
    Strand s1;
    s1.setStrand("Hellow World");
    Strand s2 = s1.substrand(1, 4);
    std::cout << "Substrand: " << s2.getStrand() << std::endl;
}

其次，你的拷贝构造函数有：

  *this = src;

它导致对此复制构造函数的无限递归调用，并且应用程序在堆栈耗尽时崩溃。这是一个修复

Strand::Strand(const char *src)
  : mStrand(0)
{
   mStrand = new char [std::strlen(src)+ 1];
   std::strcpy(mStrand, src);
}

CPP c-string切片和单元测试

1 个答案: