AGENDA
RECAP OF SESSION-1
ALL *IF*S & *BUT*S
NEVER ENDING *LOOPS*
LET’S TALK *FUN*CTIONS
Session – 2
RECAP
OF
SESSION-1
From coding to execution
Tools
Program segments
stack, heap, data, code
Data Types
unsigned/signed – long, short, char
float, double – someone to teach us
typecast
Storage Classes
auto, register, static, extern
Keywords
const, volatile
Operator precedence
NO SHORTCUTS, someone to demo their hard work
Session – 2
3
RECAP OF SESSION-1
Example#1
unsigned long a =10;
Unsigned long b = 0; b = a++ + ++a; printf("%d,%d,%d,%d",b,a++,a,++a); Example#2 unsigned long a = 20; const unsigned long b = 10; b = ++a – a--; printf("%d,%d,%d,%d",b--,a+1,--a,a++); Session – 2
4
ALL*IF*S & *BUT*S
Simple example of IF-ELSE
If (B is TRUE)
{ A = x; } else { A = y; }
It can get messy and nested quickly based on the number of conditions
Yes, we are talking about *nested* IF-ELSE
If (B is 1)
{ A = x; } else if (B is 2)
{ A = y; } else if (B is 3)
{ A = z; }
goes on …
Beware, watch out carefully the condition statement for
==
Vs
=
&&
Vs
&
||
Vs
|
Session – 2
5
ALL*IF*S & *BUT*S
Example# 1 unsigned long count = 10;
if (a) { printf(“TRUE”); } else { printf(“FALSE”); }
Example# 3 a = 5; b = 0; c = 0; if (a || (b=1) & (c == 0)) { printf(“[%d] [%d] [%d]”, ++a, ++b, ++c); } else { printf(“[%d] [%d] [%d]”, a++, b++, c++); }
Session – 2
6
ALL*IF*S & *BUT*S
7
A friendly version of *nested* IF-ELSE
Not necessary that all nested IF-ELSE can be converted to SWITCH-CASE
Each case block shall have a BREK unless if desired to do so
In case of missing BREAK, execution simply continues with next case until it finds a BREAK or SWITCH block ends
Beware and watch out for missing breaks for CASE blocks
DEFAULT, if written, will be the case if none of the listed cases match
Simple example:
Switch(B)
{ case 0: { A = y } break; case 1: { A = x } break; default: { A = 0 } break; }
Session – 2
ALL*IF*S & *BUT*S
Example# 1 unsigned long a = 9; unsigned long b = 11;
Example# 2 unsigned long a = 11; unsigned long b = 9;
switch(a)
{
case 9: { a++; --b;
}
case 11: { a = a+b; a--;
}break;
case 19: { a = b = 0;
}
default: { a = 9; b = 11;
}
} printf(“[%d] [%d]”, a, b);
Session – 2
8
ALL*IF*S & *BUT*S
9
Which is efficient - nested IF-ELSE or SWITCH-CASE?
Answer is not either way, it depends on compiler and also the CASE values grouping and range
Read for yourself at leisure
http://www.eventhelix.com/realtimemantra/Basics/CToAssemblyTransla
tion3.htm
http://books.google.co.in/books?
id=vdk4ZGRqMskC&pg=PA197&lpg=PA197&dq=ARM+assembly+for+sw itch+case&source=bl&ots=UJFgqJjZ8H&sig=T9VGU9ak6WnlqVoyOSv73d2_JQ&hl=en&ei=FleSSonIO8WIkQWJ6eC7Cg&sa=X&oi=book_result& ct=result&resnum=6#v=onepage&q=&f=false
Another way to represent a simple if (cond) { … } else { … }
if (B is TRUE) { A = x; } else { A = y; }
A = (B)? x:y;
Typically used in simple assignment statements with a decision and/or return a value based on simple decision
Session – 2
NEVER
ENDING
*LOOPS*
10
while loop
syntax: while (condition) { … }
Execution enters the loop if condition is TRUE else loop terminates
do-while loop
syntax: do { … } while(condition);
Execution always enters the loop and terminates loop at the end of loop block if condition is FALSE else loop continues
Difference between *while* loop and *do-while* loop
while
entry control loop
do-while exit control loop
Example for do-while
do{
Read a line of file;
} while (content of read has some special data, continue);
In the above example, if you don’t use do-while you may have to perform a extra read outside while and then kickoff the loop
