PHP : Validating forms and loops

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PHP Validating forms and loops
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Some things for helping you to validate input

• The isset function can be used to test if a php
  variable is passed.
• If the variable _POST'firstName' contains a
  value then isset(_POST'firstName') would
  evaluate to true.
• The is_numeric function may be useful during
  input validation to determine if the user entered
  a legitimate number.
• if you are expecting a number to be typed into an
  HTML form field named age then is_numeric(_POST'
  age' would evaluate to true

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Some things for helping you to validate input

• The empty function can be used to test if a php
  variable contains a value or not.
• If the variable _POST'firstName' contains a
  value then empty(_POST'firstName') would
  evaluate to false.
• Other validation include
• is_string(variableName)
• is_float(variableName)
• is_bool(variableName)
• is_int(variableName)

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Loops while and do-while

• num 1
• while (num lt 10)    echo "This loop is
  executed num timesltbr /gt"   num
• num 1
• do while    echo "This loop is executed num
  times ltbr /gt"   num
• (num lt 10)

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Loops for Loops

• for (num0 num lt 10 num)    echo "This
  loop is executed num timesltbr /gt"
• You can terminate explicitly with a break
  statement.
• desired 10
• for (num0 numlt100 i)
• echo "The loop is on iteration num ltbr /gt"
• if (num desired)
• echo "Found desired"
• break // if you reach this part, then the loop
  is broken

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pex4.html, pex4.php

• Redo ie. loan calculator so that

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Formula for amortization table

• Once you calculate the monthly payment, M, which
  stays the same.
• The interest payment, IP O I
• where O is the outstanding loan I is the
  monthly interest rate
• (b) Principle Paid For, P, is the amount of
  loan that went to
• principle rather than interest P M IP
• (c) The new outstanding loan, O will now be
• O O P
• ie. Previous Outstanding balance Principle
  Paid For
• Repeat the above steps (a) to (c) you need
  LOOP here to determine all periods.

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Formatting and toggling

• PHP allows up to round off numbers e.g.
• num 2.467
• num round(num, 2) // num should now
  displayed as 2.47
• Next How to do alternate colors? There is a
  concept call modulus or sometimes call quotient.
  i.e. (num 2) means take num and divided by 2
  and tell me the remainder. So the remainder would
  be 0 or 1. If it is 0 you can do one thing like
  print the current row in blue and if it is 1 you
  can print the row in gold. How to do that in php?
• echo "ltTR bgcolorbluegt" or
• echo "ltTR bgcoloryellowgt"