reference/C/FUNCTIONS/printf.html


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<title>printf function</title>

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<h1>printf function</h1>
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<p>
<b>printf</b> is used to O/P data to 
<a href="../MISC/stdfiles.html">STDOUT</a> (usually the screen). It has many 
formatting options which we shall look at in a moment. 

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<h2>printf syntax</h2>
This is an example of <b>printf</b> in its simplest form.
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  #include &lt;stdio.h&gt;

  main()
  {
    printf("This text will appear on the screen\n");  
  }
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printf is passed one formatting argument.
The unusual thing about the example (in my mind) is <b>\n</b>, this is actually 
an <a href="escape.html"> escape sequence</a> that signals a new line. Without 
it, any printf's 
that follow would O/P to the same line. 
<b>printf</b> also takes extra arguments which are inserted into the format 
string at locations marked with a <b>%</b>. 
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<pre>

  #include &lt;stdio.h&gt;

  main()
  {
    int number=42;
    printf("The answer is %i\n", number);  
  }
</pre>
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<p>
What happens here is the <b>%i</b> is seen as a 
<a href="format.html">formatting identifer</a> for the
next argument (number). In this case an integer is expected.<p>

<hr>
<h2>See also</h2>
<ol>
<li><a href="puts.html">puts</a> Much easier to use - but not as powerfull.
<li><a href="sprintf.html">sprintf</a> Same as 'printf' but O/P to a string array.
<li><a href="../CONCEPT/string.html">Strings</a>.
<li><a href="../SYNTAX/idioms.html#printf">A dead handy printf idiom.</a>.
</ol>


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<address>Martin Leslie 
</address><p>
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