Engineering Problem Solving with C Fundamental Concepts

1
Engineering Problem Solving with C Fundamental
Concepts

• Chapter 3
• Control Structures and Data Files

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Algorithm Development
3
Structured Programming

• Sequence
• Selection
• Repetition

yes
no
4
Conditional Expressions
5
Relational Operators

• equality
• ! non equality
• lt less than
• gt greater than
• lt less than equal to
• gt greater than equal to

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Logical Operators

• ! not
• and
• or

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Operator Precedence

• lt lt gt gt
• !

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Selection Statements
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Selection Statements

• if
• if else
• switch

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If statement

• if(Boolean expression)
• statement //single statement
• if(Boolean expression)
• //more than one statement
• statement1
• .
• statement n

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If statement - examples

• if (xgt0)
• k
• if(xgt0)
• xsqrt(x)
• k

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if - else statement

• if(Boolean expression)
• statement
• else
• statement
• if(Boolean expression)
• statement block
• else
• statement block

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nested if-else
if(x gt y) if(y lt z) k else m else j

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Practice!
int x9, y7, z2, k0, m0, j0 if(x gt y) if(y
lt z) k else m else j What are the
values of j, k and m?
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Switch Statement
switch(expression) case constant statement(
s) break case constant statement(s) bre
ak / default is optional/ default statem
ent(s)
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Switch Statement

• Expression must be of type integer or character
• The keyword case must be followed by a constant
• break statement is required unless you want all
  subsequent statements to be executed.

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Practice!
Convert the following nested if/else statements
to a switch statement if (rank1 ?? rank2)
printf("Lower division \n") else if
(rank3 ?? rank4) printf("Upper division
\n") else     if (rank5)
printf("Graduate student \n") else
printf("Invalid rank \n")
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Loop Structures
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repetition

• while statement
• do while statement
• for statement

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while statement

• while(expression)
• statement
• while(expression)
• statement
• statement
• .

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do while

• do
• statement
• while(expression)
• do
• statement1
• statement2
• .
• while(expression)
• note - the expression is tested after the
  statement(s) are executed, so statements are
  executed at least once.

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for statement

• for(initialization test increment/decrement)
• statement
• for(initialization test increment/decrement)
• statement
• statement
• .

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for statement
initalize
test
increment/ decrement
true
statement(s)
statement(s)
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for statement - examples

• int sum 0
• for(int I1Ilt10I2)
• sum sum I
• int fact 1
• for(int n5ngt1n- -)
• fact fact n

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Practice!

• Determine the number of times that each of the
  following for loops are executed.
• for (k3 klt20 k)
• statements
• for (k3 klt20 k)
• statements
• for (count-2 countlt14 count)
• statements

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break statement

• break
• terminates loop
• execution continues with the first statement
  following the loop

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continue statement

• continue
• forces next iteration of the loop, skipping any
  remaining statements in the loop

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Data Files
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Data Files

• Each data file must have a file pointer
• file pointer must be defined
• FILE sensor1
• FILE balloon
• file pointer must be associated with a specific
  file using the fopen function
• sensor1 fopen(sensor1.dat, r)
• balloon fopen(balloon.dat, w)

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I/O Statements

• Input file - use fscanf instead of scanf
• fscanf(sensor1, 1f lf, t, motion)
• Output file - use fprint instead of printf
• fprintf(balloon, f f f\n, time, height,
  velocity)

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Reading Data Files

• counter controlled loop
• for loop
• sentinel controlled loop
• while loop
• end of file controlled loop
• while loop