InputOutput

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Chapter 9

• Input/Output
• Operations Functions

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Input/Output

• Input/output functions provided by I/O library.
• Header file is stdio.h.
• Two general I/O functions printf() for output,
  scanf() for input.

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Formatting output printf()

• Format
• printf(format-control-string, print-list)
• Example
• printf("That equals .2f centimetres.\n", cm)

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Formatting output printf()

• printf() displays the value of its format control
  string
• after substituting in left-to-right order the
  value of the expressions in the print list for
  their conversion specifications in the format
  string and
• after replacing escape sequences by their
  meanings

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Formatting output printf()

• Example
• sum 20 count 30
• printf("d divided by d equals f\n",
• sum, count, (float)sum/count)
• Output
• 20 divided by 3 equals 6.666667

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Conversion specification
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Conversion specification
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Conversion specification
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Conversion specification
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Field Width Precision

• Field place where an argument is displayed
• Field width number of characters in field
• Field width and precision are specified between
  the symbol and the conversion specifier.
• Example 9.3f
• Display right justified if field width is larger
  than what the value requires. For numeric data,
  if field width is too small, it is ignored.

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Field Width Precision
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Field Width Precision

• Precision
• for specifier d minimum number of digits
  (default 1)
• for e, E and f number of digits after decimal
  point
• for g and G maximum number of significant digits
• for s maximum number of characters

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Field Width Precision
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Flags

• To provide more formatting features

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Flags
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Flags
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Flags
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Flags
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Flags
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Literals Escape Sequences

• Non-printing characters \n, \0.
• Escape sequences to represent special characters.
  Examples \n, \t.
• Literals to appear in string ", \, etc. Need to
  be escaped since " is used to delimit strings,
  and \ to start an escape sequence.

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Literals Escape Sequences
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Literals Escape Sequences
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Formatting input scanf()

• Format
• printf(format-control-string, scan-list)
• Example
• scanf("2f", inch)

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Conversion specification
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Conversion specification
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Conversion specification
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Conversion specification
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Field Width
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Assignment Suppression Character
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Homework

• Try exercises behind chapter 9.