Program control statements in c#
Download as PPTX, PDF1 like932 views
The document discusses different types of program control statements in 3 categories: selection statements (if, switch), iteration statements (for, while, do-while, foreach), and jump statements (break, goto, continue, return, throw). It provides details on switch statements, including their general form and use of break. It also covers fallthrough in switch statements, which allows continuous execution of consecutive cases without break, and how to force fallthrough using goto. The document concludes with an overview of foreach loops, which iterate over an expression similar to for loops but do not allow changing the iteration variable.
Program control statements in c#
- 1. Program Control Statements Dr. Neeraj Kumar Pandey
- 2. Introduction There are three types of program control statements:- 1. Selection Statements if switch 2. Iteration Statements for while do-while foreach 3.Jump Statements break goto continue return throw
- 3. Switch Statement The switch statement tests the value of a given variable (or expression) against a list of case values and when match is found, a block of statements associated with that case is executed. The general form of switch statement is :- switch(expression) { case value-1: block-1 break; case value-2: block-1 break case value-n: block-1 break default: default –block break; }
- 4. Switch Statement(Contd.) using System; class bulb { public static void Main() { Console.WriteLine("Select your choice"); Console.WriteLine("London"); Console.WriteLine("Bombay"); Console.WriteLine("Paris"); Console.WriteLine("Type your choice"); String name=Console.ReadLine(); switch(name) { case " Bombay": Console.WriteLine("Bombay:Guide5"); break; case " London": Console.WriteLine("London:Guide10"); break; case " Paris": Console.WriteLine("Paris:Guide15"); break; default: Console.WriteLine("Invalid Choice"); break;
- 5. Fallthrough in Switch Statement In the absence of break statement in a case block, if the control moves to the next case block without any problem, it is known as ‘FALLTHROUGH’. ‘FALLTHROUGH’ is permitted in C,C++ and JAVA. But C# doesn't permit automatic fallthrough, if the case block contains executable code. switch(m) { case 1: x=y; case 2: x=y+m; default : x=y-m; } is an error in C#.
- 6. Fallthrough in Switch Statement(Contd..) If we want two consecutive case blocks to be executed continuously, we have to force the process by using the goto statement. switch(m) { case 1: x=y; goto case 2; case 2: x=y+m; goto default; default: x=y-m; break; }
- 7. Fallthrough in Switch Statement(Contd..) The goto mechanisms enable us to jump backward and forward between cases and therefore arrange labels arbitrarily: Switch(m) { default: x=y-m; break; case 2: x=y+m; goto default; case 1: x=y; goto case 2; }
- 8. Foreach statement The foreach statement is similar to the for statement but implemented differently. foreach(type variable in expression) { Body of the Loop } public static void Main() { foreach(string s in args) { Console.WriteLine(s); } } We cannot change the iteration variable during execution.