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<title>20.5.2 Arguments </title>
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<a name="1204539"> </a><font color="#003366" face="Verdana, Arial, Helvetica, sans-serif">20.5.2 Arguments</font>
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<a name="1204540"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">The arguments of a command or procedure consist of all the text following the command or procedure name up to the next statement terminator. This may be a comma or a new-line or a right bracket ("<font size=2 face=Courier><strong>)</strong></font>" or "<font size=2 face=Courier><strong>}</strong></font>") corresponding to a left bracket <strong>before</strong> the function call.</font>
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<a name="1204541"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">This can produce surprising results for the programmer used to C syntax. For example:</font>
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<a name="1204542"> </a><font size=2 face=Courier><strong>> proc addtwo { $$= $1+2}<br>> x= addtwo(8) + 7<br>> write (x)<br>10<br></strong></font>
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<a name="1204546"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">Here the "<font size=2 face=Courier><strong>+ 7</strong></font>" is treated as an extra unused argument to <font size=2 face=Courier><strong>addtwo</strong></font>. This can be avoided as follows:</font>
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<a name="1204547"> </a><font size=2 face=Courier><strong>> proc addtwo { $$= $1+2}<br>> x= (addtwo(8)) + 7<br>> write (x)<br>17<br></strong></font>
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<a name="1204551"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">Arguments to commands and procedures are normally passed as strings. A string may be enclosed in quotation marks (<font size=2 face=Courier><strong>"</strong></font>), and must be enclosed in quotation marks if it contains spaces. Inside quoted strings, the back slash character (<font size=2 face=Courier><strong>\</strong></font>) is interpreted as the escape character, as in C quoted strings. Thus <font size=2 face=Courier><strong>"\n"</strong></font> is a new line character, <font size=2 face=Courier><strong>"\t"</strong></font> is a tab character, <font size=2 face=Courier><strong>"\\"</strong></font> is the back slash character, and <font size=2 face=Courier><strong>"\33"</strong></font> is the character with ASCII code octal 33.</font>
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<a name="1204552"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">If an argument is enclosed in brackets <font size=2 face=Courier><strong>( )</strong></font>, the command language attempts to evaluate it as an expression yielding an integer, before passing it as a argument. If the parameters are omitted, the expression is passed as a string.</font>
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<a name="1204553"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">For example:</font>
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<a name="1204554"> </a><font size=2 face=Courier><strong>> x = 3<br>> write x<br>x<br>> write (x)<br>3<br></strong></font>
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<a name="1204559"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">The command language also accepts comma-separated lists of arguments within brackets, analogous to the normal C function calling syntax. In this case each argument is treated as if it were enclosed in its own set of brackets.</font>
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<a name="1204560"> </a><font size=2 face="Verdana, Arial, Helvetica, sans-serif">For example:</font>
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<a name="1209443"> </a><font size=2 face=Courier><strong>>write (4) (3) "string" (2) (1)<br>4 3 string 2 1<br>>write (4, 3, "string", 2, 1)<br>4 3 string 2 1<br>><br></strong></font>
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