itextsharp pdf to image c# : Adding image to pdf form application Library tool html asp.net wpf online book8-part1796

1.9 Exercises
51
a = = 2; b b = = 1; c c = = 2
from math h import t sqrt
q = = b*b - 4*a*c
q_sr = = sqrt(q)
x1 = = (-b + + q_sr)/2*a
x2 = = (-b - - q_sr)/2*a
print x1, , x2
Correct the program m so that t it solvesthe given n equation.Filename:
find_errors_roots.py.
Adding image to pdf form - C# PDF Field Edit Library: insert, delete, update pdf form field in C#.net, ASP.NET, MVC, Ajax, WPF
Online C# Tutorial to Insert, Delete and Update Fields in PDF Document
add photo to pdf form; add form fields to pdf online
Adding image to pdf form - VB.NET PDF Field Edit library: insert, delete, update pdf form field in vb.net, ASP.NET, MVC, Ajax, WPF
How to Insert, Delete and Update Fields in PDF Document with VB.NET Demo Code
add image to pdf form; create pdf forms
C# PDF insert image Library: insert images into PDF in C#.net, ASP
Insert images into PDF form field. To help you solve this technical problem, we provide this C#.NET PDF image adding control, XDoc.PDF for .NET.
create a form in pdf; add an image to a pdf form
VB.NET PDF Page Insert Library: insert pages into PDF file in vb.
Support adding PDF page number. Offer PDF page break inserting function. DLLs for Adding Page into PDF Document in VB.NET Class. Add necessary references:
add image field to pdf form; add date to pdf form
Loopsandlists
2
Thischapterexplainshowrepetitivetasksinaprogramcanbeauto-
matedbyloops.Wealsointroducelistobjectsforstoringandprocessing
collectionsofdatawithaspecificorder.Loopsandlists,togetherwith
functionsandiftestsfromChapter3,laythefundamentalprogramming
foundationfortherestofthebook.Theprogramsassociatedwiththe
chapterarefoundinthefoldersrc/looplist1.
2.1Whileloops
OurtasknowistoprintoutaconversiontablewithCelsiusdegreesin
thefirstcolumnofthetableandthecorrespondingFahrenheitdegrees
inthesecondcolumn.Suchatablemaylooklikethis:
-20 -4.0
-15
5.0
-10 14.0
-5 23.0
0 32.0
5 41.0
10 50.0
15 59.0
20 68.0
25 77.0
30 86.0
35 95.0
40 104.0
2.1.1Anaivesolution
TheformulaforconvertingCdegreesCelsiustodegreesFahrenheitis
F=9C/5+32.Sinceweknowhowtoevaluatetheformulaforonevalue
ofC,wecanjust repeatthesestatementsasmanytimesasrequired
1
http://tinyurl.com/pwyasaa/looplist
53
VB.NET PDF Library SDK to view, edit, convert, process PDF file
PDF document to/from supported document and image forms. to define text or images on PDF document and Capable of adding PDF file navigation features to your VB
edit pdf form; adding images to pdf forms
C# PDF Page Insert Library: insert pages into PDF file in C#.net
By using reliable APIs, C# programmers are capable of adding and inserting (empty) PDF page or pages from various file formats, such as PDF, Tiff, Word, Excel
add fillable fields to pdf online; changing font size in pdf form
54
2 Loopsandlists
forthetableabove.Usingthreestatementsperlineintheprogram,for
compactlayoutofthecode,wecanwritethewholeprogramas
C = = -20; ; F F = = 9.0/5*C + 32; ; print t C, , F
C = = -15; ; F F = = 9.0/5*C + 32; ; print t C, , F
C = = -10; ; F F = = 9.0/5*C + 32; ; print t C, , F
C = = -5; F F = = 9.0/5*C + 32; ; print t C, , F
C =
0; F F = = 9.0/5*C + 32; ; print t C, , F
C =
5; F F = = 9.0/5*C + 32; ; print t C, , F
C = = 10; F F = = 9.0/5*C + 32; ; print t C, , F
C = = 15; F F = = 9.0/5*C + 32; ; print t C, , F
C = = 20; F F = = 9.0/5*C + 32; ; print t C, , F
C = = 25; F F = = 9.0/5*C + 32; ; print t C, , F
C = = 30; F F = = 9.0/5*C + 32; ; print t C, , F
C = = 35; F F = = 9.0/5*C + 32; ; print t C, , F
C = = 40; F F = = 9.0/5*C + 32; ; print t C, , F
Runningthisprogram(whichisstoredinthefilec2f_table_repeat.py),
demonstratesthattheoutputbecomes
-20 -4.0
-15 5.0
-10 14.0
-5 23.0
0 32.0
5 41.0
10 50.0
15 59.0
20 68.0
25 77.0
30 86.0
35 95.0
40 104.0
Thisoutputsuffersfromsomewhatuglyformatting,butthatproblem
canquicklybefixedbyreplacingprint C, F bya print statement
basedonprintfformatting.Wewillreturntothisdetaillater.
Themainproblemwiththeprogramaboveisthatlotsofstatements
areidenticalandrepeated.Firstofallitisboringtowritethissortof
repeatedstatements,especiallyifwewantmanymoreCandvalues
inthetable.Second,theideaofthecomputeristoautomaterepetition.
Therefore,allcomputerlanguageshaveconstructstoefficientlyexpress
repetition.Theseconstructsarecalledloopsandcomeintwovariantsin
Python:whileloopsandforloops.Mostprogramsinthisbookemploy
loops,sothisconceptisextremelyimportanttolearn.
2.1.2Whileloops
Thewhileloopisusedtorepeatasetofstatementsaslongasacondition
istrue.Weshallintroducethiskindofloopthroughanexample.The
taskistogenerate therowsof the table of andvalues. The C
valuestartsat20andisincrementedby5aslongasC≤40.Foreach
valuewecomputethecorrespondingvalueandwriteoutthetwo
temperatures.Inaddition,wealsoaddalineofdashesaboveandbelow
thetable.
Thelistoftaskstobedonecanbesummarizedasfollows:
C# Word - Insert Image to Word Page in C#.NET
VB.NET Protect: Add Password to PDF; VB.NET Form: extract value VB.NET How-to, VB.NET PDF, VB.NET Word, VB It's a demo code for adding image to word page using
cannot save pdf form; create pdf forms
C# PDF insert text Library: insert text into PDF content in C#.net
Supports adding text to PDF in preview without adobe reader installed in ASP.NET. Powerful .NET PDF edit control allows modify existing scanned PDF text.
adding text fields to a pdf; convert word document to editable pdf form
2.1 Whileloops
55
•Printlinewithdashes
•C=−20
•WhileC≤40:
– F=
9
5
C+32
– PrintCandF
– IncrementCby5
•Printlinewithdashes
Thisisthealgorithmofourprogrammingtask.Thewayfromadetailed
algorithmtoafullyfunctioningPythoncodecanoftenbemadevery
short,whichisdefinitelytrueinthepresentcase:
print ’------------------’
# table heading
C = = -20
# start t value for C
dC = = 5
# increment of f C in n loop
while C C <= 40:
# loop p heading with h condition
F = = (9.0/5)*C + + 32
# 1st t statement t inside loop
print C, F
# 2nd statement inside loop
C = = C C + dC
# 3rd statement inside loop
print ’------------------’
# end d of f table e line e (after loop)
AveryimportantfeatureofPythonisnowencountered:theblockof
statementstobeexecutedineachpassofthewhileloopmustbeindented.
Intheexampleabovetheblockconsistsofthreelines,andalltheselines
musthaveexactlythesameindentation.Ourchoiceofindentationin
thisbookisfourspaces.Thefirststatementwhoseindentationcoincides
withthatofthewhilelinemarkstheendoftheloopandisexecuted
aftertheloophasterminated.Inthisexamplethisisthefinalprint
statement.Youareencouragedtotypeinthecodeaboveinafile,indent
thelastlinefourspaces,andobservewhathappens(youwillexperience
thatlinesinthetableareseparatedbyalineofdashes:––––).
Manynovice Python programmersforget the colon at t the e end of
thewhileline-thiscolonisessentialandmarksthebeginningofthe
indented blockof statementsinsidethe loop.Later,we willseethat
therearemanyothersimilarprogramconstructionsinPythonwhere
thereisaheadingendingwithacolon,followedbyanindentedblockof
statements.
Programmersneedtofullyunderstandwhatisgoingoninaprogram
andbeabletosimulatetheprogrambyhand.Letusdothiswiththe
programsegmentabove.First,wedefinethestartvalueforthesequence
ofCelsiustemperatures:C = -20.WealsodefinetheincrementdCthat
willbeaddedtoCinsidetheloop.ThenweentertheloopconditionC
<= 40.ThefirsttimeCis-20,whichimpliesthatC <= 40(equivalentto
C≤40inmathematicalnotation)istrue.Sincetheloopconditionistrue,
weentertheloopandexecutealltheindentedstatements.Thatis,we
computeFcorrespondingtothecurrentCvalue,printthetemperatures,
andincrementCbydC.Forsimplicity,wehaveusedaplainprint C, F
withoutanyformattingsothecolumnswillnotbealigned,butthiscan
easilybefixedlater.
C# PDF Library SDK to view, edit, convert, process PDF file for C#
Capable of adding PDF file navigation features to your C# program. You may easily generate thumbnail image from PDF. C#.NET: PDF Form Field Edit.
change font size in pdf form field; changing font in pdf form
C# PowerPoint - Insert Image to PowerPoint File Page in C#.NET
C# Read: PDF Image Extract; C# Write: Insert text into PDF; C# Write: Add Image to PDF; C# Protect: Add Password to PDF; C# Form: extract value from fields; C#
pdf form save in reader; create a pdf form from excel
56
2 Loopsandlists
Thereafter,weenterthesecondpassintheloop.Firstwecheckthe
condition:Cis-15andC <= 40isstilltrue.Weexecutethestatements
intheindentedloopblock,Cbecomes-10,thisisstilllessthanorequal
to40,soweentertheloopblockagain.Thisprocedureisrepeateduntil
Cisupdatedfrom40to45inthefinalstatementintheloopblock.When
wethentestthecondition,C <= 40,thisconditionisnolongertrue,and
theloopisterminated.Weproceedwiththenextstatementthathas
thesameindentationasthewhilestatement,whichisthefinalprint
statementinthisexample.
Newcomerstoprogrammingaresometimesconfusedbystatements
like
C = = C C + + dC
Thislinelookserroneousfromamathematicalviewpoint,butthestate-
ment isperfectlyvalidcomputer code,becausewe firstevaluate the
expressionontheright-handsideoftheequalitysignandthenletthe
variableontheleft-handsiderefertotheresultofthisevaluation.In
ourcase,CanddC are twodifferentintobjects.TheoperationC+dC
resultsinanewintobject,whichintheassignmentC = C+dCisbound
tothenameC.Beforethisassignment,Cwasalreadyboundtoanint
object,andthisobjectisautomaticallydestroyedwhenCisboundto
anewobjectandtherearenoothernames(variables)referringtothis
previousobject(ifyoudidnotgetthislastpoint,justrelaxandcontinue
reading!).
Sinceincrementingthevalueofavariableisfrequentlydoneincom-
puterprograms,thereisaspecialshort-handnotationforthisandrelated
operations:
C += dC
# equivalent to o C C = = C + + dC
C -= dC
# equivalent to o C C = = C - - dC
C *= dC
# equivalent to o C C = = C*dC
C /= dC
# equivalent to o C C = = C/dC
2.1.3Booleanexpressions
Inourfirstexampleonawhileloop,weworkedwithaconditionC <=
40,whichevaluatestoeithertrueorfalse,writtenasTrueorFalsein
Python.Othercomparisonsarealsouseful:
C == 40
# C C equals 40
C != 40
# C C does s not equal l 40
C >= 40
# C C is greater than n or equal l to 40
C > > 40
# C C is greater than n 40
C < < 40
# C C is less s than 40
Notonlycomparisonsbetweennumberscanbeusedasconditionsin
whileloops:anyexpressionthathasaboolean(TrueorFalse)value
canbeused.Suchexpressionsareknownaslogicalorbooleanexpressions.
VB.NET Image: How to Draw Annotation on Doc Images with Image SDK
multi-page TIFF, Microsoft Office Word and PDF file programmer, you might need some other image annotating tutorials besides adding annotation using VB
add photo to pdf form; adding text to a pdf form
C# PDF Password Library: add, remove, edit PDF file password in C#
Following are examples for adding password to a plain PDF passwordSetting.IsAnnot = true; // Allow to fill form. IsAssemble = true; // Add password to PDF file
can reader edit pdf forms; convert word to editable pdf form
2.1 Whileloops
57
Thekeywordnotcanbeinsertedinfrontofthebooleanexpressionto
changethevaluefromTruetoFalseorfromFalsetoTrue.Toevaluate
not C == 40,wefirstevaluateC == 40,forC = 1thisisFalse,and
thennotturnsthevalueintoTrue.Ontheopposite,ifC == 40isTrue,
not C == 40becomesFalse.MathematicallyitiseasiertoreadC != 40
thannot C == 40,butthesetwobooleanexpressionsareequivalent.
Booleanexpressionscanbecombinedwithandandortoformnew
compoundbooleanexpressions,asin
while x x > > 0 0 and d y y <= = 1:
print x, y
If cond1 andcond2 are twobooleanexpressionswithvaluesTrueor
False,thecompoundbooleanexpressioncond1 and cond2isTrueif
bothcond1andcond2areTrue.Ontheotherhand,cond1 or cond2
isTrueifatleastoneoftheconditions,cond1orcond2,isTrue
Remark
InPython,cond1 and cond2 orcond1 or cond2returnsoneof
theoperandsandnotjustTrueorFalsevaluesasinmostother
computerlanguages.Theoperandscond1orcond2canbeexpres-
sionsorobjects.Incaseofexpressions,thesearefirstevaluatedto
anobjectbeforethecompoundbooleanexpressionisevaluated.For
example,(5+1) or -1evaluatesto6(thesecondoperandisnot
evaluatedwhenthefirstoneisTrue),and(5+1) and -1evaluates
to-1.
Herearesomemoreexamplesfromaninteractivesessionwherewe
justevaluatethebooleanexpressionsthemselveswithoutusingthemin
loopconditions:
>>> x x = = 0; ; y y = 1.2
>>> x x >= 0 0 and y y < < 1
False
>>> x x >= 0 0 or r y < < 1
True
>>> x x > > 0 0 or y y > > 1
True
>>> x x > > 0 0 or not y y > > 1
False
>>> -1 1 < x x <= = 0
# -1 1 < < x x and x <= = 0
True
>>> not (x > > 0 0 or y y > > 0)
False
Inthelastsampleexpression,notappliestothevalueoftheboolean
expression inside the parentheses: x>0 isFalsey>0 isTrue, so the
combinedexpressionwithorisTrue,andnotturnsthisvaluetoFalse.
58
2 Loopsandlists
ThecommonbooleanvaluesinPythonareTrue,False,0(false),and
anyintegerdifferentfromzero(true).Toseesuchvaluesinaction,we
recommenddoingExercises2.21and2.17.
Booleanevaluationofanobject
AllobjectsinPythoncaninfactbeevaluatedinabooleancontext,
andallareTrueexceptFalse,zeronumbers,andemptystrings,
lists,anddictionaries:
>>> s s = = ’some string’
>>> bool(s)
True
>>> s s = = ’’ ’ # # empty y string
>>> bool(s)
False
>>> L L = = [1, 4, 6]
>>> bool(L)
True
>>> L L = = []
>>> bool(L)
False
>>> a a = = 88.0
>>> bool(a)
True
>>> a a = = 0.0
>>> bool(a)
False
Essentially,if atestsifaisanon-emptyobjectorifitisnon-zero
value.SuchconstructionsarefrequentinPythoncode.
Erroneousthinking about t boolean expressions isone e of f the most
commonsourcesoferrorsincomputerprograms,soyoushouldbecareful
every time e you encounter r abooleanexpressionand check that t it is
correctlystated.
2.1.4Loopimplementationofasum
Summationsfrequentlyappearinmathematics.Forinstance,thesine
functioncanbecalculatedasapolynomial:
sin(x)≈x−
x3
3!
+
x5
5!
x7
7!
+··· ,
(2.1)
where 3! = 3· 2· 1, 5! = 5· 4· 3· 2· 1, etc., are factorial expressions.
Computingk! =k(k− 1)(k− 2)···2· 1 is done bymath.factorial(k).
An infinite number of terms are needed on the right-hand side of (2.1)
for the equality sign to hold. With a finite number of terms, we obtain
an approximation tosin(x), which is well suited for being calculated in a
program since only powers and the basic four arithmetic operations are
involved. Say we want to compute the right-hand side of (2.1) for powers
2.2 Lists
59
up toN = 25. Writing out and implementing each one of these terms is
atedious job that can easily be automated by a loop.
Computation of the sum in (2.1) by awhile loop in Python, makes
use of (i) a counterk that runs through odd numbers from 1 up to some
given maximum powerN, and (ii) a summation variable, says, which
accumulates the terms, one at a time. The purpose of each pass of the
loop is to compute a new term and add it tos. Since the sign of each
term alternates, we introduce a variablesign that changes between1
and 1 in each pass of the loop.
The previous paragraph can be precisely expressed by this piece of
Python code:
x = 1.2 # assign some value
N = 25
# maximum power in sum
k = 1
s = x
sign = 1.0
import math
while k < N:
sign = - sign
k = k + 2
term = sign*x**k/math.factorial(k)
s = s + term
print ’sin(%g) = %g (approximation with %d terms)’ % (x, s, N)
The best way to understand such a program is to simulate it by hand.
That is, we go through the statements, one by one, and write down on a
piece of paper what the state of each variable is.
When the loop is first entered,k < N implies1 < 25, which isTrue
so we enter the loop block. There, we computesign = -1.0,k = 3,
term = -1.0*x**3/(3*2*1)) (note that sign is float so we always
have float divided byint), ands = x - x**3/6, which equals the
first two terms in the sum. Then we test the loop condition:3 < 25
isTrue so we enter the loop block again. This time we obtainterm =
1.0*x**5/math.factorial(5),whichcorrectlyimplementsthethird
term in the sum. At some point,k is updated to from23 to25 inside
the loop and the loop condition then becomes25 < < 25, which isFalse,
implying that the program jumps over the loop block and continues
with theprint statement (which has the same indentation as thewhile
statement).
2.2 Lists
Up to now a variable has typically contained a single number. Sometimes
numbers are naturally grouped together. For example, all Celsius degrees
in the first column of our table from Section 2.1.2 could be conveniently
stored together as a group. A Python list can be used to represent such a
60
2 Loops and lists
group of numbers in a program. With a variable that refers to the list, we
can work with the whole group at once, but we can also access individual
elements of the group. Figure 2.1 illustrates the difference between an
intobjectandalistobject.Ingeneral,alistmaycontainasequence
of arbitrary objects in a given order. Python has great functionality for
examining and manipulating such sequences of objects, which will be
demonstrated below.
var1
21
var2
0
20
1
21
2
29
3
4.0
Fig. 2.1 Illustrationoftwovariables: var1referstoan intobjectwithvalue21,created
by the statementvar1 = 21, andvar2 refers to alist object with value[20, 21, 29,
4.0],i.e.,three intobjectsandone floatobject,createdbythestatementvar2 = [20,
21, 29, 4.0].
2.2.1 Basic list operations
To create a list with the numbers from the first column in our table, we
just put all the numbers inside square brackets and separate the numbers
by commas:
C = [-20, -15, -10, -5, 0, 5, 10, 15, 20, 25, 30, 35, 40]
The variableC now refers to alist object holding 13 list elements. All
list elements are in this case int objects.
Every element in a list is associated with an index, which reflects the
position of the element in the list. The first element has index 0, the
second index 1, and so on. Associated with theC list above we have 13
indices, starting with 0 and ending with 12. To access the element with
index 3, i.e., the fourth element in the list, we can writeC[3]. As we see
from the list, C[3] refers to an int object with the value −5.
Elements in lists can be deleted, and new elements can be inserted
anywhere. The functionality for doing this is built into the list object
and accessed by a dot notation. Two examples areC.append(v), which
appends a new element v to the end of the list, andC.insert(i,v),
which inserts a new element v in position numberi in the list. The
number of elements in a list is given bylen(C). Let us exemplify some
list operations in an interactive session to see the effect of the operations:
Documents you may be interested
Documents you may be interested