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<head><title>File << Thing -- print to a file</title>
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<div><h1>File << Thing -- print to a file</h1>
<div class="single"><h2>Synopsis</h2>
<ul><li><div class="list"><dl class="element"><dt class="heading">Usage: </dt><dd class="value"><div><tt>f << x</tt><br/><tt> << x</tt></div>
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<li><span>Operator: <a href="__lt_lt.html" title="a binary operator (file output, ...)"><<</a></span></li>
<li><div class="single">Inputs:<ul><li><span><tt>f</tt>, <span>a <a href="___File.html">file</a></span>, <span>a <a href="___String.html">string</a></span>, <span>a <a href="___List.html">list</a></span>, or <a href="_null.html" title="the unique member of the empty class">null</a></span></li>
<li><span><tt>x</tt>, <span>a <a href="___Thing.html">thing</a></span></span></li>
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<li><div class="single">Consequences:<ul><li>The object <tt>x</tt> is prepared for printing (with <a href="_net.html" title="format for printing, as a net">net</a>) and printed on the output file(s) <tt>f</tt>. If <tt>f</tt> is a string, then it is interpreted as a filename and an output file is opened, used, and returned, unless a single open file with the same name already exists, in which case it is used and returned. Filenames starting with <tt>!</tt> or with <tt>$</tt> are treated specially, see <a href="_open__In__Out.html" title="open an input output file">openInOut</a>. If <tt>f</tt> is a list, then the output operation is performed on each one. If <tt>f</tt> is <a href="_null.html" title="the unique member of the empty class">null</a>, then the output is discarded; thus <a href="_null.html" title="the unique member of the empty class">null</a> is useful as a dummy output file. If <tt>f</tt> is omitted, as in the second usage line, then the output is sent to <a href="_stdio.html" title="the standard input output file">stdio</a>, and it will appear (usually) on the screen.</li>
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<li><div class="single">Outputs:<ul><li><span><span>a <a href="___File.html">file</a></span>, the output file(s) used</span></li>
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<div class="single"><h2>Description</h2>
<div><p>Parsing of <a href="__lt_lt.html" title="a binary operator (file output, ...)"><<</a> associates leftward, so that several objects may be displayed with an expression such as <tt>f<<x<<y<<z</tt>.</p>
<table class="examples"><tr><td><pre>i1 : stderr << "-- hi there --" << endl
-- hi there --
o1 = stderr
o1 : File</pre>
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<tr><td><pre>i2 : << "-- ho there --" << endl
-- ho there --
o2 = stdio
o2 : File</pre>
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<tr><td><pre>i3 : fn = temporaryFileName()
o3 = /tmp/M2-22789-1</pre>
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<tr><td><pre>i4 : fn << "hi there" << endl << close
o4 = /tmp/M2-22789-1
o4 : File</pre>
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<tr><td><pre>i5 : get fn
o5 = hi there</pre>
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<tr><td><pre>i6 : R = QQ[x]
o6 = R
o6 : PolynomialRing</pre>
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<tr><td><pre>i7 : f = (x+1)^10
10 9 8 7 6 5 4 3 2
o7 = x + 10x + 45x + 120x + 210x + 252x + 210x + 120x + 45x + 10x +
------------------------------------------------------------------------
1
o7 : R</pre>
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<tr><td><pre>i8 : << f
10 9 8 7 6 5 4 3 2
x + 10x + 45x + 120x + 210x + 252x + 210x + 120x + 45x + 10x + 1
o8 = stdio
o8 : File</pre>
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<tr><td><pre>i9 : fn << f << close
o9 = /tmp/M2-22789-1
o9 : File</pre>
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<tr><td><pre>i10 : get fn
o10 = 10 9 8 7 6 5 4 3 2
x + 10x + 45x + 120x + 210x + 252x + 210x + 120x + 45x + 10x
+ 1</pre>
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<tr><td><pre>i11 : fn << toExternalString f << close
o11 = /tmp/M2-22789-1
o11 : File</pre>
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<tr><td><pre>i12 : get fn
o12 = x^10+10*x^9+45*x^8+120*x^7+210*x^6+252*x^5+210*x^4+120*x^3+45*x^2+10*x+
1</pre>
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<tr><td><pre>i13 : value get fn
10 9 8 7 6 5 4 3 2
o13 = x + 10x + 45x + 120x + 210x + 252x + 210x + 120x + 45x + 10x
-----------------------------------------------------------------------
+ 1
o13 : R</pre>
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<tr><td><pre>i14 : removeFile fn</pre>
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<div class="single"><h2>See also</h2>
<ul><li><span><a href="_stdio.html" title="the standard input output file">stdio</a> -- the standard input output file</span></li>
<li><span><a href="_stderr.html" title="the standard error output file">stderr</a> -- the standard error output file</span></li>
<li><span><a href="_endl.html" title="end an output line">endl</a> -- end an output line</span></li>
<li><span><a href="_close.html" title="close a file">close</a> -- close a file</span></li>
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