Examine return values of method calls

 

,You can see the return values of methods in the Autos window when you step over or out of a method call. This is supported for the .NET Framework (version 4.0 and higher) and in C++. This functionality is useful when the result of a method call is not stored in a local variable, for example withmethod chaining (such as a method called on the object returned by another method).

View method return values in the Autos window (C#)

Given the following code:

static void Main(string[] args)
{
    string str = "abcdef";
    string start = getHalf(str).Insert(0, "ghij");
}

private static string getHalf(string orig)
{
    return orig.Substring(orig.Length / 2);
}

If you set a breakpoint on the line of code inside getHalf(), then press F10, execution stops at the end of getHalf(). At this point you should see two values in the Autos window, the string’s Length and the result of the Substring() method:

Note

In some circumstances, if the return value is null, you may not be able to use this technique.

You can also examine the return value of a .NET Framework method call by typing $ReturnValue in the Immediate window or a Watch window after you have stepped over or out of the method call. To open the Immediate window, choose Debug / Windows / Immediate (CTRL + ALT+ I).

Note

You must have the legacy expression evaluators turned on for $ReturnValue to be recognized (Tools / Options / Debugging / Use the legacy C# and VB expression evaluators). Otherwise, you can use $ReturnValue1.

View method return values in the Autos window (C++)

Given the following code:

using namespace std;

string getHalf(string orig) {
    return orig.substr(orig.length() / 2);
};

int main() {
    string str1 = "abcdef";
    string start = getHalf(str1).insert(3, "ghi");
}

1. If you set a breakpoint on the line of code inside getHalf(), then press F10, execution stops at the end of getHalf(). At this point you should see two values in the Autos window, the string’s Length and the result of the Substring() method: