技术经验

做var old = /*value*/
function loop(){if (/*value*/ != old){ //check if the value is not old//do stuff}old = /*value*/ //set old to valuerequesta...

技术经验

NullReferenceException is a C# version of NullPointerException. To handle and catch it in C#, use try-catch.The below example shows that a variable is set to nu...