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| author | Tobias Klauser <tklauser@distanz.ch> | 2008-01-27 11:37:44 +0100 |
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| committer | Tobias Klauser <tklauser@xenon.tklauser.home> | 2008-01-27 11:37:44 +0100 |
| commit | 7e0f021a9aec35fd8e6725e87e3313b101d26f5e (patch) | |
| tree | b1cacc4b24393f517aeb4610e9e1021f954307a8 /reference/C/SYNTAX/while.html | |
Initial import (2.0.2-6)2.0.2-6
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| -rw-r--r-- | reference/C/SYNTAX/while.html | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/reference/C/SYNTAX/while.html b/reference/C/SYNTAX/while.html new file mode 100644 index 0000000..ef083f9 --- /dev/null +++ b/reference/C/SYNTAX/while.html @@ -0,0 +1,160 @@ +<html> +<head> +<title>The WHILE keyword.</title> +<script language="JavaScript"> +</script> +</head> +<body bgcolor="#ffffcc"> +<hr> +<center><h1>The WHILE keyword.</h1></center> +<hr> +The <b>while</b> keyword is related to <a href=do.html>do</a> +and <a href=for.html>for</a>. Its purpose is to repeatedly execute +a <a href="statements.html#blocks">block</a> of statements. Here is +an example : + +<p> +<center> +<table border=1 width="80%" bgcolor="ivory"> +<tr> +<td> +<pre> + + main() + { + int i=5; + + while(--i) + { + printf(" i is %d\n", i); + } + } +</pre> +</td> +</tr> +</table> +</center> +<p> + +The expression <b>i--</b> is evaluated and if its +<a href="../CONCEPT/true_false.html">true</a> the statements in the +<a href="statements.html#blocks">block</a> are executed. +The loop continues until the expression is false (zero). +The result will look like this: + +<p> +<center> +<table border=1 width="80%" bgcolor="ivory"> +<tr> +<td> +<pre> + + i is 4 + i is 3 + i is 2 + i is 1 +</pre> +</td> +</tr> +</table> +</center> +<p> + +It is important to note that the statements +on a <b>while</b> will not get executed if the first evaluation of the +expression is FALSE. If you do not want this to happen you may prefer +to use the <a href="do.html">do</a> statement. + +<hr> +<p> +Now consider the next example. + +<p> +<center> +<table border=1 width="80%" bgcolor="ivory"> +<tr> +<td> +<pre> + + main() + { + int i=5; + + while(--i); + { + printf(" i is %d\n", i); + } + } +</pre> +</td> +</tr> +</table> +</center> + + +The result will look like this: + + +<p> +<center> +<table border=1 width="80%" bgcolor="ivory"> +<tr> +<td> +<pre> + + i is 0 +</pre> +</td> +</tr> +</table> +</center> + +<p> +This is because of the <b>;</b> on the end of the <b>while</b> +statement which means the <b>while</b> will loop (executing NULL statements) +until <b>i</b> is zero. Execution will then continue down the program +(to the printf). +<p> + +<hr> +<h2>Examples:</h2> + +<img src="../../GRAPHICS/computer.gif" align=left alt="o"> +<a href="../EXAMPLES/while.c">Basic <b>while</b></a>. +<br clear=left> + +<hr> +<h2>See also:</h2> +<ul> +<li><a href="while.html">for</a> keyword. +<li><a href="do.html">do</a> keyword. +<li><a href="break.html">break</a> keyword. +<li><a href="continue.html">continue</a> keyword. +</ul> + + +<p> + +<hr> +<p> +<center> +<table border=2 width="80%" bgcolor="ivory"> +<tr align=center> +<td width="25%"> +<a href="../cref.html"> Top</a> +</td><td width="25%"> +<a href="../master_index.html"> Master Index</a> +</td><td width="25%"> +<a href="keywords.html"> Keywords</a> +</td><td width="25%"> +<a href="../FUNCTIONS/funcref.htm"> Functions</a> +</td> +</tr> +</table> +</center> +<p> +<hr> +<address>Martin Leslie +</address><p> +</body> +</html> |