Intro to Computing Concepts

1
Intro to Computing Concepts

• Lecture 6
• Mark Fontenot

2
Objectives

• New Stream Manipulators
• Advanced Math Functions

3

• Stream Manipulators

4
Stream Manipulators
Quick Review
What is one stream manipulator weve seen so far?
cout ltlt Hello ltlt endl
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setw

• setw(x)
• print fields of a specified width

int main() int x 28 cout ltlt ( ltlt
setw(5) ltlt x ltlt )ltltendl return 0
( 28) _
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setprecision

• setprecision(x)
• controls the number of significant digits (total
  number of digits before and after decimal point
  when used alone)
• Remains in effect until explicitly changed

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fixed

• fixed
• Forces cout to print digits in fixed-point
  notation (versus scientific notation)
• Remains in effect until explicitly change

Note When fixed and setprecision are used
together, argument of setprecision is the total
of digits to appear after the decimal point.
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setprecision fixed

• include ltiostreamgt
• include ltiomanipgt
• using namespace std
• int main()
• float a 1.23456,
• b 1.226,
• c 3.1
• cout ltlt setprecision(2) ltlt fixed
• cout ltlt Figuresltlt\n------------\n
• cout ltlt setw(8) ltlt a ltlt endl
• cout ltlt setw(8) ltlt b ltlt endl
• cout ltlt setw(8) ltlt c ltlt endl
• return 0

New header file
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setprecision fixed

• Figures
• ------------
• 1.23
• 1.23
• 3.10

Notice the 1st and 2nd numbers were rounded.
10
showpoint

• showpoint forces cout to include trailing zeros
  when printing

float x 123.4, y 456.0 cout ltlt
setprecision(6) ltlt showpoint ltlt x ltlt endl ltlt
y
123.400456.000_
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setw with cin

• Only works with strings
• Can NOT use with any number-based type (int,
  float, etc). cin will take all numbers.
• Tell the program how many characters to extract
  from the input stream

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setw with cin

• includeltiostreamgt
• includeltiomanipgt
• using namespace std
• int main()
• char word5
• cout ltlt Enter a word
• cin gtgt setw(5) gtgt word
• cout ltlt You entered
• ltlt word ltlt endl
• return 0

Enter a word Eureka
You entered Eure _
word
\0
E
u
r
e
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Review

• Stream Manipulators
• setw
• setprecision
• fixed
• showpoint

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Other uses of cin
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getline
Allows the programmer to accept strings
with spaces in them
char string20 cin.getline(string, 19, \n)
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cin.getline

• Allows you to read a complete line of input
• Reads characters up to when user presses ltentergt
• Will accept spaces and tabs also

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cin.getline

• include ltiostreamgt
• include ltiomanipgt
• int main()
• char string15
• cout ltlt Enter a sentence
• cin.getline(string, 15)
• coutltltYou entered ltlt string ltltendl
• return 0

string
Enter a sentence See spot run!
You entered See spot run!
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cin.get

• cin.get(ch) retrieves only one character from the
  buffer

int main() char myChar coutltltEnter a
char cin.get(myChar) coutltltYou entered
ltltmyCharltltendl return 0
Enter a char x
You entered x _
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cin.get
int main() char myChar coutltltPress Enter
cin.get(myChar) coutltltThank youltltendl
return 0
keyboard buffer
\n
Press Enter Enter
Thank you _
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cin.get and cin gtgt
int main() char myChar int x
coutltltEnter a number cin gtgt x
coutltltEnter a character ltltendl
cin.get(myChar) coutltltThank you!ltltendl
return 0
x
keyboard buffer
159
159\n
Enter a number 159Enter
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cin.get and cin gtgt
int main() char myChar int x
coutltltEnter a number cin gtgt x
coutltltEnter a character ltltendl
cin.get(myChar) coutltltThank you!ltltendl
return 0
159
x
keyboard buffer
\n
myChar
\n
Enter a number 159Enter Enter a character
Thank you _
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cin.ignore()

• cin.ignore(n, c)
• Used to ignore a certain number of characters
• n is the number of characters to ignore
• when cin.ignore(n,c) encounters character c, it
  will stop ignoring characters
• cin.ignore()
• will only ignore the next character

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cin.get and cin gtgt
int main() char myChar int x
coutltltEnter a number cin gtgt x
cin.ignore() coutltltEnter a character
ltltendl cin.get(myChar) coutltltThank
you!ltltendl return 0
159
x
keyboard buffer
myChar
\n
Enter a number 159Enter Enter a character
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cin.get and cin gtgt
int main() char myChar int x
coutltltEnter a number cin gtgt x
cin.ignore() coutltltEnter a character
ltltendl cin.get(myChar) coutltltThank
you!ltltendl return 0
159
x
keyboard buffer
m
myChar
m\n
Enter a number 159Enter Enter a character
mEnter
25
cin.get and cin gtgt
int main() char myChar int x
coutltltEnter a number cin gtgt x
cin.ignore() coutltltEnter a character
ltltendl cin.get(myChar) coutltltThank
you!ltltendl return 0
159
x
keyboard buffer
m
myChar
\n
Enter a number 159Enter Enter a character
mEnter
Thank you _
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• Math Functions

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include ltcmathgt

• abs
• y abs(x)
• Returns the absolute value of the argument.
• The argument and the return value are integers

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include ltcmathgt

• cos
• y cos(x)
• Returns the cosine of the argument
• The arugument should be an angle expressed in
  radians.
• The argument and the return value are doubles

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include ltcmathgt

• log
• y log(x)
• Returns the natural logarithm of the argument
• The argument and the return value are doubles

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include ltcmathgt

• sqrt
• y sqrt(x)
• Returns the square root of the argument.
• The argument and the return value are doubles

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include ltcmathgt

• pow
• y pow(x,y)
• Returns the value of x raised to the power of y.
• The argument and the return value are integers

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Exercise
Write a program to ask the user for a and b and
calculate c based on the following formula.
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Questions?

• ?