C＃string.length> 0看作布尔值

Question

I am new to C# but not to programming. When I compare the lengths of two strings in the code below, I get the error:

Operator '&' cannot be applied to operands of type 'bool' and 'int'

Apparently string1.Length > 0 is seen as a boolean in this context.

How should I perform this comparison?

if (string1.Length > 0 & string2.Length = 0)
{
    //Do Something
}

Answer 1

The reason for the error is because you have written = when you meant == . In C#

string1.Length > 0 & string2.Length = 0

means

(string1.Length > 0) & (string2.Length = 0)

The type of the left side is bool and the type of the right side is int , which cannot be & -ed together, hence the error. Of course even if you managed to get past that, Length cannot be the target of an assignment either.

Use == to test for equality. = is assignment.

Consider also using && instead of & . The meaning of x & y is "evaluate both, the result is true if both are true and false otherwise". The meaning of x && y is "evaluate the left side; if it is false then the result is false so do not evaluate the right side. If the left side is true then proceed as & does."

Answer 2

When applied to integers, the & operator in C# is a bitwise AND , not a logical AND . Also = is an assignment, not an equality comparison operator. The string1.Length > 0 expression is indeed an expression of boolean type, while the assignment is integer (because 0 is integer).

What you need is

if (string1.Length > 0 && string2.Length == 0)

Answer 3

You probably meant to do this:

if (string1.Length > 0 && string2.Length == 0)
{
    //Do Something
}

In C#, the = operator is just for assignment. The == is used for equality comparisons. You probably also want to use the && operator instead of & ( && will skip the second condition if the first condition evaluates to false).

However, if really want to 'compare the lengths of the strings', you can just do this:

if (string1.Length > string2.Length)
{
    //Do Something
}

Answer 4

这将解决您的问题。

if(string1.Length > 0 && string2.Length == 0)

Answer 5

I think you want a == for your equality test? C# assignment returns a value (as in C) .