Question

我必须编写一个比较三个文本文件的代码，但我不知道为什么我不会打印任何东西：

#include <iostream>
#include <cstring>
#include <string>
#include <fstream>
using namespace std;

int main (int argc, char *argv[])
{
    ifstream mousefile;
    mousefile.open(argv[1]);
    string mouse_dna;
    getline(mousefile, mouse_dna);

    ifstream humanfile;
    humanfile.open(argv[2]);
    string human_dna;
    getline(humanfile, human_dna);

    ifstream unknownfile;
    unknownfile.open(argv[3]);
    string unknown_dna;
    getline(unknownfile, unknown_dna);

    int len = mouse_dna.size();
    int mouseDistance = 0, humanDistance = 0;

    for(int i=0; i<len; i++)
        if(mouse_dna[i] != unknown_dna[i])
            mouseDistance++;
            return mouseDistance;
    for(int i=0; i<len; i++)
        if(human_dna[i] != unknown_dna[i])
            humanDistance++;
            return humanDistance;


    double similarity_scoreH = (len - humanDistance) / len; 
    double similarity_scoreM = (len - mouseDistance) / len; 
    cout << "MouseCompare = " << similarity_scoreM << endl;
    cout << "HumanCompare = " << similarity_scoreH << endl;

    if (similarity_scoreH == similarity_scoreM)
        cout << "identity cannot be determined" << endl;
    else if (similarity_scoreH > similarity_scoreM)
        cout << "human" << endl;
    else if (similarity_scoreM > similarity_scoreH)
        cout << "mouse" << endl;


}

它编译正确，并且不会出现任何错误，但是当我把它作为：

时

./DNA mouseDNA.txt humanDNA.txt unknownDNA.txt

它仍然无能为力。我感谢任何帮助。谢谢！

Answer 1

它不打印任何内容，因为它在打印指令（return mouseDistance;或return humanDistance;）之前返回。通过在每个return语句之前打印进度消息，使您的函数更加详细。

Answer 2

正如已经指出的那样，你太早回来了。我修改你的代码：

我在if块和block之间放置括号。
最后我有一份回复声明。

这是一个开始。您可能必须添加更多检查，例如，如果文件正确打开。

#include <iostream>
#include <cstring>
#include <string>
#include <fstream>
using namespace std;

int main (int argc, char *argv[])
{
    ifstream mousefile;
    mousefile.open(argv[1]);
    string mouse_dna;
    getline(mousefile, mouse_dna);

    ifstream humanfile;
    humanfile.open(argv[2]);
    string human_dna;
    getline(humanfile, human_dna);

    ifstream unknownfile;
    unknownfile.open(argv[3]);
    string unknown_dna;
    getline(unknownfile, unknown_dna);

    int len = mouse_dna.size();
    int mouseDistance = 0, humanDistance = 0;

    for(int i=0; i<len; i++)
    {
        if(mouse_dna[i] != unknown_dna[i])
        {
            mouseDistance++;
        }
    }
    for(int i=0; i<len; i++)
    {
        if(human_dna[i] != unknown_dna[i])
        {
            humanDistance++;
        }
    }


    double similarity_scoreH = (len - humanDistance) / len; 
    double similarity_scoreM = (len - mouseDistance) / len; 
    cout << "MouseCompare = " << similarity_scoreM << endl;
    cout << "HumanCompare = " << similarity_scoreH << endl;

    if (similarity_scoreH == similarity_scoreM)
        cout << "identity cannot be determined" << endl;
    else if (similarity_scoreH > similarity_scoreM)
        cout << "human" << endl;
    else if (similarity_scoreM > similarity_scoreH)
        cout << "mouse" << endl;


    return 0;
}

Answer 3

你使用arg [1]，arg [2]和arg [3]。您可能需要arg [0]，arg [1]和arg [2]。

有人可以告诉我为什么这段代码没有打印任何东西？

3 个答案: