String Comparator Operator C ++

Question

简单的问题。

cout << "What color do you want to search for?" << endl;
string key;
string ARRAY[5];
cin >> key;

for (int i = 0; i < 5; i ++)
{
  if (ARRAY[i] == key)
       cout << "Found " << key << endl;
  else
       cout << key << " not found" << endl;
}

我有一个有5种颜色的数组，但无论输入到达else函数。我使用正确的比较运算符来比较字符串吗？我知道java的等价物是.equals（）。任何帮助将不胜感激！

编辑：这是我的整个代码，更清楚地显示了问题。

#include <iostream>
#include <fstream>
#include <string>
#include <algorithm>

using namespace std;

string ARRAY[5];

int main()
{
    ofstream myFile; //creates a file writer object
    myFile.open("searchfile.txt"); //creates a file named "searchfile.txt"

myFile << "Orange" <<endl << "Green" <<endl << "Blue" <<endl << "Red" <<endl << "Purple" <<endl;
myFile.close();



string key;
string LIST;
ifstream myFile2; //creates a file reader object
myFile2.open("searchfile.txt");

while (!myFile2.eof()) //if not at the end of the file, continue reading
{
    for (int i = 0; i < 5; i++)
    {
        getline(myFile2, LIST); //stores the value in string variable 'LIST'
        ARRAY[i] = LIST;
        cout << ARRAY[i] <<endl;
    }//end for
}//end while
myFile2.close();

cout <<"What do you want to search for?" <<endl;
cin >> key;
key = "Red";
for (int i = 0; i < 5; i++)
{
    if (ARRAY[i].equal(key))

        cout <<"Found " << key <<endl;

    else
        cout << key <<" not found" <<endl;
    //end if
}
return 0;

}

Answer 1

即使更改比较线，您在以下块中使用的逻辑也不正确。

for (int i = 0; i < 5; i++)
{
    if (ARRAY[i] == key)
        cout <<"Found " << key <<endl;
    else
        cout << key <<" not found" <<endl;
}

我们说key == "Purple"。在最后一项之前你不会看到比赛。同时，您将为所有其他颜色打印not found字符串。将逻辑更改为：

bool found = false;
for (int i = 0; i < 5; i++)
{
   if (ARRAY[i] == key)
   {
      found = true;
      break
   }
}

if ( found )
   cout <<"Found " << key <<endl;
else
   cout << key <<" not found" <<endl;

您可以使用std::find（感谢@LightnessRacesinOrbit）使代码紧凑：

if (std::find(std::begin(ARRAY), std::end(ARRAY), key) != std::end(ARRAY))
   cout << "Found " << key << endl;
else
   cout << key << " not found" << endl;

Answer 2

代码在语义上对于您想要执行的操作是正确的。 请注意cin >> key：如果您输入的内容包含空格，key将仅包含输入的第一个字词。

Answer 3

http://www.cplusplus.com/reference/string/string/compare/

使用字符串比较

实施例

list.OrderBy(func).ToList()