C# 错误：并非所有代码路径都返回值

C# error: not all code paths return a value

提问by NullReferenceException

I have declared a method in another class and it has an error "not all code paths return a value"

我在另一个类中声明了一个方法，它有一个错误“并非所有代码路径都返回一个值”

I would like it to return a true or false value to the main program.

我希望它向主程序返回一个真值或假值。

But when I declare my method, public static void, another error produces, a return keyword must not be followed by an object expression.

但是当我声明我的方法时，public static void会产生另一个错误，返回关键字后面不能跟一个对象表达式。

public class FileSearch
{
    public static Boolean SearchFiles(string path1, string path2)
    {
        bool isIdentical = false;
        string content1 = null;
        string content2 = null;

        DirectoryInfo d1 = new DirectoryInfo(path1);
        DirectoryInfo d2 = new DirectoryInfo(path2);

        foreach (FileInfo f1 in d1.GetFiles("*.txt", SearchOption.AllDirectories))
        {
            foreach (FileInfo f2 in d2.GetFiles("*.txt", SearchOption.AllDirectories))
            {
                content1 = (File.ReadAllText(f1.DirectoryName + "\" + f1));
                content2 = (File.ReadAllText(f2.DirectoryName + "\" + f2));

                isIdentical = content1.Equals(content2, StringComparison.Ordinal);

                if (isIdentical == false)
                {
                    return false;
                }
                else
                {
                    return true;
                }
            }
        }
    }
}

采纳答案by germi

Your method SearchFilesonly returns a value if isIdenticalis false. If it's true, the method never returns.

SearchFiles如果isIdenticalis ，您的方法仅返回一个值false。如果是true，则该方法永远不会返回。

To remove this error, write something like this:

要消除此错误，请编写如下内容：

public static Boolean SearchFiles(string path1, string path2)
{
    // do some work to assign a value to isIdentical
    // note that it would be idiomatic to just write "return isIdentical;" in this case
    // I keep it explicitly here for demonstration purposes 
    if (isIdentical == false)
    {
        return false;
    }
    else
    {
        return true;
    }
}

To your second question: If you declare your method as public static voidyou must not returnany value. voidmeans that the method will not give you anything back.

对于你的第二个问题：如果你将你的方法声明为public static void你不能有return任何价值。void意味着该方法不会给你任何回报。

You might want to have a look at this: Methods (C# Programming Guide), especially the part about return values.

您可能想看看这个：方法（C# 编程指南），尤其是关于返回值的部分。

Edit: Since you have your if / elsein a foreachloop, you need something like this:

编辑：因为你有if / else一个foreach循环，你需要这样的东西：

public static Boolean SearchFiles(string path1, string path2)
{
    foreach(var item in collection)
    {
        // do some work to assign a value to isIdentical
        if (isIdentical == false)
        {
            return false;
        }
        else
        {
            return true;
        }
    }
    // in case the collection is empty, you need to return something
    return false;
}

回答by Anand

public static Boolean SearchFiles(string path1, string path2)
{
    if (isIdentical == false)
    {
        return false;
    }
    return true or false;
}

回答by David Pilkington

You need to return something if the if condition is not true

如果 if 条件不为真，你需要返回一些东西

you can try this

你可以试试这个

return isIdentical 

and remove your if statement

并删除您的 if 语句

so that it looks like this

所以它看起来像这样

public class FileSearch
{
        public static Boolean SearchFiles(string path1, string path2)
        {
            //Do your other work here
            return isIdentical ;
        }
}

回答by Farrukh Afzaal Kurd

public static Boolean SearchFiles(string path1, string path2)
{

    if(isIdentical == false)
    {
        return false;
    }
    else
    {
        return true;
    }

}

回答by Mohammad tanvirul islam

you can try this code....i think it will help you.

你可以试试这个代码......我认为它会帮助你。

public class FileSearch
    {
        public static Boolean SearchFiles(string path1, string path2)
        {
            bool isIdentical = false;
            string content1 = null;
            string content2 = null;
bool result=false;

            DirectoryInfo d1 = new DirectoryInfo(path1);
            DirectoryInfo d2 = new DirectoryInfo(path2);

            foreach (FileInfo f1 in d1.GetFiles("*.txt", SearchOption.AllDirectories))
            {
                foreach (FileInfo f2 in d2.GetFiles("*.txt", SearchOption.AllDirectories))
                {
                    content1 = (File.ReadAllText(f1.DirectoryName + "\" + f1));
                    content2 = (File.ReadAllText(f2.DirectoryName + "\" + f2));

                    isIdentical = content1.Equals(content2, StringComparison.Ordinal);

                    if (isIdentical == false)
                    {
                       break;
                    }
                    else
                    {
                        result=true;break;

                    }
break;
            }
return result;
        }

    }

回答by Kiran Waghmare

put this at the end of method

把它放在方法的末尾

return isIdentical;

返回是相同的；

u are not returning any value. This may work

你没有返回任何值。这可能有效