Is it OK to use assignments in expressions?

Class ReportClass
{
 public string ReportName {get; set;}
}

displayReport(ReportClass.ReportName = cmbReportName.SelectedValue.ToString())

ReportClass.ReportName = cmbReportName.SelectedValue.ToString();
displayReport(ReportClass.ReportName);

string line;
while ((line = reader.ReadLine()) != null)
{
    // Do something with line
}

Foo(new Bar { X=1, Y=2 });

var a = 0;
var b = 0;

// This makes a *and* b equals to 1
a = b = 1;

// This line prints 3 and a is now equals to 3
Console.WriteLine(a = 3);

// This line prints 7 and a and b is now equals to 7
Console.WriteLine(a = b = 7);

displayReport(
    ReportClass.ReportName = cmbReportName.SelectedValue.ToString());

var reportName = cmbReportName.SelectedValue.ToString();

displayReport(ReportClass.ReportName = reportName);

int a, b, c;
a = b = c = 0;

while ((packetPos = Packet.FindStart(buffer, nextUnconsideredPos)) > -1)

packetPosition = Packet.FindStart(buffer, nextUnconsideredPosition);
while (packetPosition > -1)
{
  ...
  packetPosition = Packet.FindStart(buffer, nextUnconsideredPosition);
}