比较文件中的字符串

Question

我在文本文件中给出了一列字符串，我必须将它们相互比较 - 我想比较第一个字符串和下面的所有字符串，然后回到第二个字符串并比较它全部在下面等等。问题是我不知道如何编写它的代码

Answer 1

使用嵌套循环做你期望的;

#include <iostream> 
#include <fstream> 
#include <vector> //include this to use vector 

using namespace std; 

int main() { 

    //to take input from the file 
    ifstream fin; 

    //to read the same strings into 2 arrays so we can loop it appropriately 
    //by taking one string and comparing it to all below it. 
    vector <string> line1; 
    vector <string> line2; 

    //to hold a line of string 
    string temp; 

    //replace this with with your file 
    fin.open("hello.txt"); 

    //to check if file cannot be opened or does not exist 
    if(!fin.is_open()) { 
     cout << "file could not be opened"; 
    } 

    //strings are inserted into element of these 2 vectors 
    //(Internally, vectors use a dynamically allocated array to store their elements in adjacent memory locations) 
    //that is why i decided to use vectors. Also, using the push_back method 
    //to insert the strings into both arrays means we don't have to specify the size of the array 
    while (getline(fin, temp)) { 
     line1.push_back(temp); 
     line2.push_back(temp); 
    } 


    //nested loop is used to make sure one string is used to operate 
    //on all the strings in the file and move to the next to do same 
    //and so on... 
    for (unsigned int i = 0; i < line1.size(); i++) { 
     for (unsigned int j = 0; j < line2.size(); j++) { 
      //you can compare first string with all below here however you want to do it 
      //I just did this so you see how it behaves 
      cout << line1[i] << " = " << line2[j] << endl; 
     } 
    } 

    return 0; 
} 

Answer 2

最简单的方法是使用CMD的Linux像grep的：

// 1路

grep -w -v -f file1.log file.2 > mach.log 

// 2路

grep -w -f file1.log file.2 > mach.log 

你千万不能忘记旗帜的意思：

-w， --word-regexp 只选择那些包含构成整个单词的匹配的行。测试是匹配子字符串必须位于行首，或者以非单词组成字符开头。 类似地，它必须位于行尾，或者后面跟着一个非单词组成字符。单词组成字符是字母，数字和下划线。

-v， - 反转匹配 反转匹配的意义，选择不匹配的行。

-f FILE，--file = FILE 从FILE获取模式，每行一个。如果此选项多次使用或与-e（--regexp）选项结合使用，请搜索所有给定的模式。空文件包含零模式，因此 什么都不匹配。