检查字符串是否相同 C++
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Checking if strings are the same c++
提问by Michael Kimin Choo
For my case, I have to check if 2 strings are the same. The probelm I'm getting, is that No matter what I input, I'm getting a true value regardless of what I put in.
就我而言，我必须检查 2 个字符串是否相同。我得到的问题是，无论我输入什么，无论我输入什么，我都会得到一个真正的价值。
bool Dictionary::checkIfWordExists(string input){
for(int counter=0;counter<234;counter++){
if(input.compare(getWordFromDictionary(counter))){
return true;
}
}
return false;}
For testing purposes I used a do loop like this to type in stuff to test in comparison to the dictionary.txt file that I loaded.
出于测试目的，我使用了这样的 do 循环来输入要测试的内容，与我加载的 dictionary.txt 文件进行比较。
do{
cout<<"enter something you sexy beast"<<endl;
string test;
cin>>test;
if(loadedDictionary.checkIfWordExists(test)){
cout<<"yes"<<endl;
}else{
cout<<"no"<<endl;
}
}while(true);
回答by Overv
That's because compare actually returns 0when the strings are equal. If the strings are not equal, it will return a value higher or lower and the if will evaluate to true, as you are seeing.
那是因为0当字符串相等时compare 实际上返回。如果字符串不相等，它将返回一个更高或更低的值，并且 if 将评估为 true，如您所见。
It is common in languages like Java and C# to use methods like equalsto compare non-primitives, but in C++ it is preferably to just use ==.
在 Java 和 C# 等语言中，使用equals比较非原语等方法是很常见的，但在 C++ 中，最好只使用==.
回答by andre
There should be an operator==for std::stringavailable for a more natural feeling comparison.
应该有一个operator==forstd::string可用于更自然的感觉比较。
if(input == getWordFromDictionary(counter)) { ... }
回答by yasouser
You need to explicitly compare the result of comparewith 0. Here is what the return values mean:
您需要明确比较comparewith的结果0。以下是返回值的含义：
0 => The compared strings are equal
0 => 比较的字符串相等
<0 => Either the value of the first character that does not match is lower in the compared string, or all compared characters match but the compared string is shorter.
<0 => 要么是比较字符串中第一个不匹配的字符的值较小，要么所有比较字符都匹配但比较字符串较短。
>0 => Either the value of the first character that does not match is greater in the compared string, or all compared characters match but the compared string is longer.
>0 => 要么比较字符串中第一个不匹配的字符的值越大，要么所有比较字符都匹配但比较字符串较长。
See here for the detailed explanation on std::string::compare.
有关std::string::compare的详细说明，请参见此处。
