OK my fellow Teenaged programmers.... can someone xplain in DEPTH what a switch statement is and what assertions are.... I dont understand the definition that this damn book gives... thanx

There is no depth to the idea of switch statements. They pick from a list of choices for the value of an expression and run something.

An assertion is something that you say is true at some point in a program, and it had better be true or something has gone wrong in the program.

A switch statment is an alternative to many if else statments. Basic use could be:

int num = 1;

switch(num)
{
case 0:
{
cout << "The number is zero";
}
case 1:
{
cout << "The number is one";
}
case 2:
{
cout << "The number is two";
}
default:
{
cout << "error"
}
}

the output of that switch statment would be 'The number is one'

a switch statment tests a variable and exectes whichever code block corresponds to the value of the variable. it the example above the integer variable num had a value of 1. the statment then went thru the list of expressions. num wasnt 0 so the first block was ignored. the second block (testing against value 1) was correct, therefore the block was executed. the rest of the stament was then ignored as the correct block was already found. if the variable num was initialized with a value of say, 4 the default: code block is executed. Its job is so that if the whole switch statment doesnt test for a variables current value, there is always smething executed(usfull for error checking).
Hope this clafies it slighty

Marc

Hey Diego,
Explanation by metamorphic is more then enough. Just know that switch only takes int or chars as the case conditions.
If u r planning 2 take some exams in c/c++. Be sure 2 check what happens when breaks(not all) r added/removed and the use of effects etc in switch. Try to find books by Yashwant Kanetkar(Test ur c skills, exploring c etc) 2 clear all the doubts

Thanks guys.... yall always help me out when the book cant!

Marc: you didn't tried this program, did you?
I did, you didn't put in a break at the end of each case
case 1:
{
cout << "The number is one";
break; <<<<<==========================
}

If you don't, it will execute the right case and every case after it.

RedX

A switch is just like a bunch of if-else statements, actually if there was no switch statement a programmer would just use if-else.

switch statements are much more efficient with many possible cases and non-stupid compilers. For instance, they can be implemented with automatic binary searches or jump tables.

It may seem stupid Psion, but I really don't know what a jump table is. Plz elaborate. I hope Diego too will like know!

All right. Here's some C code and pseudo-assembly.

switch (bob)
{
case 0:
bob = 1;
break;
case 1:
bob = 2;
break;
case 2:
bob = 3;
break;
}

... can translate as:

jumpto Table + (bob)
case0:
load 1 -> (bob)
jumpto done
case1:
load 2 -> (bob)
jumpto done
case2:
load 3 -> (bob)
done:
...

Table: .data case0, case1, case2

yeah the the freak is a jump table... is that another reserved word in C++... ahh brother!!

OH. Thanks Psion.

hah thanks red, no i didnt try it. but thanks anyway. nice to know someone is looking out for me :)

Hey Diego, Seems u have got a lot of answers 4 ur question.
But what is it with the book that u have. If it is not able to clearly explain something as simple as a switch statement , i would suggest u chuck it out of the window. Try a book called "Programming in C++" by Robert Lafore. It is the best C++ book, that I have laid my hands on!!!!!

-Vikram

try "C++ How to Program, 3e" its a good book

it costs 80 dollars with tax, so be rich

Lol!!! Oh thats ok Faisal..... Ill download a tutorial off the internet for free!!

Hey Diego Dude,
I presume u r in college.... Why dont u try to get the book Faisal talked about from ur college library.... or try to persuade ur college to buy that book....

Vikram.

Most people here aren't in college.

thanx Psion... that really makes me feel dumb!... lol