Arrays in c unit iii chapter 1 mrs.sowmya jyothi

ARRAYS IN C
C PROGRAMMING
MRS.SOWMYA JYOTHI

1. UNIT III
CHAPTER 1-ARRAYS
REFERENCE: PROGRAMMING IN C BY BALAGURUSWAMY
MRS. SOWMYA JYOTHI, SDMCBM, MANGALORE

2. Array:Arrayisaderiveddatatype.
•Whenitisnecessarytostoremorethanonevalue
underavariable,usercanmakeuseofarray.
•Anarrayisafixed-sizesequencecollectionof
elementsofthesamedatatype.
•Itissimplyagroupingoflike-datatype.

3. Different types of arrays :
There are three types of arrays. They are,
1.One dimensional array.
2.Two dimensional array.
3.Multidimensional array.

4. One dimensional array :
•Alistofitemscanbegivenonevariablenameusing
onlyonesubscriptandsuchavariableiscalled
aonedimensionalarray.
Example:intnumber[5];
• Hereintheexample,5valueofthevariable
numbercanbekeptunderthesinglevariable
number.

5. Declarationofonedimensionalarray:Likeanyother
variable,arraysmustbedeclaredbeforetheyareused.
•Thegeneralformofarraydeclarationis,
• typevariable_name[size];
Thetypespecifiesthetypeofelementsthatwillbecontained
inthearray,suchasint,floatetc.Thesizeindicatesthe
maximumnumberofelementthatcanbestoredinsidethe
array.
Forexample,
floatheight[50];
Thisdeclarestheheighttobeanarraycontaining50real
numbers.

6. Twodimensionalarray:
•Whenbyusinganarray,usercanstoretwovalue,
eachforarowandacolumnunderavariable,the
arrayisthencalledatwodimensionalarray.
Here,usercanuseinfinitenumberofrowsand
columns.
Twodimensionalarraysaredeclaredasfollows,
• typearray_name[rowsize][columnsize];
•Eg:inta[3][4];

7. Multidimensionalarray:
•Callowsarraysofthreeormoredimensions.Theexactlimit
isdeterminedbythecompiler.
•Thegeneralformofamultidimensionalarrayis,
• typearrayname[s1][s2]......[sn];
Where snis the size of the dimension.
For example,
• intsurvey[3][5][12]
surveyis a three dimensional array declared to contain 180
integer type elements.

8. Initialization of one dimensional array :
Afteranarrayisdeclared,itselementsmustbe
initialized.Anarraycanbeinitializedeitherofthe
followingstages,
1.At compile time.
2.At run time.

9. Compiletimeinitialization:
Usercaninitializetheelementsofanarrayinthesame
wayastheordinaryvariableswhentheyaredeclared.This
iscompiletimeinitialization.
Thegeneralformisasfollows,
• typearrayname[size]={listofvalues};
Thevaluesinthelistareseparatedbycommas.
Forexample,
• intnumber[3]={0,0,0};
Thiswilldeclarethevariablenumberasanarrayofsize3
andwillassign0toeachelement.

10. Run time initialization :
•An array can be explicitly initialized at run time. This approach is
usually applied for initializing large arrays. For example,
for(i=0;i<100;i=i+1)
{
if (i<50)
sum[i]=0.0;
else
sum[i]=1.0;
}
The first 50 elements of the array sum are initialized to zero while the
remaining 50 elements are initialized to 1.0 at run time.

11. Initialization of two dimensional array :
Liketheonedimensionalarrays,twodimensionalarraysmaybe
initializedbyfollowingtheirdeclarationwithalistofinitial
valuesenclosedinbraces.
Forexample,
inttable[2][3]={0,0,0,1,1,1};
Thisinitializestheelementsofthefirstrowto0andthesecond
rowto1.Thisstatementcanalsobewrittenas,
• inttable[2][3]={{0,0,0},{1,1,1}};
•This can also be written as,
inttable[2][3]={
{0,0,0},
{1,1,1}
};

12. marks [0][0]
35.5
Marks [0][1]
40.5
Marks [0][2]
45.5
marks [1][0]
50.5
Marks [1][1]
55.5
Marks [1][2]
60.5
marks [2][0] Marks [2][1] Marks [2][2]
marks [3][0] Marks [3][1] Marks [3][2]
Elements of multi dimension arrays:
A 2 dimensional array marks [4][3] is shown below figure.
The first element is given by marks [0][0] contains 35.5 &
second element is marks [0][1] and contains 40.5 and so on.

13. min=a[1] i.emin=36
i=2
a[2]< min 55<36 NO
i=3
A[3]< min 23<36 YES
min=23 SWAP
i=4
A[4]<min 12<23 YES
min=12 SWAP
i=5
A[5]<min 95<12 NO
12345

14. max=a[1] i.emax=36
i=2
a[2]> max 55>36 YES
max=a[2] max=55 SWAP
i=3
A[3]>max 23>55 NO
max=55 No change in max
i=4
A[4]>max 12>55 NO
i=5
A[5]>max 95>55 YES
Max=a[5] max=95 SWAP
i=6
A[6]>max 44>55 NO

15. •The Fibonacci Sequence is the series of numbers:
•0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ...
...
•Fibonacci Series is apattern of numbers where each number is
the result of addition of the previous two consecutive numbers.
•First 2 numbers start with 0 and 1.
•The third numbers in the sequence is 0+1=1. The 4th number is
the addition of 2nd and 3rd number i.e. 1+1=2 and so on.
The next number is found by adding up the two numbers before
it:
•the 2 is found by adding the two numbers before it (1+1),
•the 3 is found by adding the two numbers before it (1+2),
•the 5 is (2+3),
•and so on!

16. f1 f2 f3
f1 f2
f3
{
f3 = f1 + f2;
printf(" %d", f3);
f1 = f2;
f2 = f3;
}

18. How to reverse a number mathematically.
•Step 1 —Isolate the last digit(rem) in number.
rem= number % 10
The modulo operator (%) returns the remainder of a divison.
•Step 2 —Append lastDigit(rem) to reverse.
reverse= (reverse * 10) + rem
•Step 3-Remove last digit from number.
number = number / 10.