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<TITLE>RE: [LCP]Very Small Doubt...</TITLE>
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<P><FONT SIZE=2>> int n;</FONT>
<BR><FONT SIZE=2>> char *str, *str1;</FONT>
<BR><FONT SIZE=2>> scanf("%s", str);</FONT>
<BR><FONT SIZE=2>> scanf("%s", str1);</FONT>
<BR><FONT SIZE=2>> scanf("%d",&n);</FONT>
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<P><FONT SIZE=2>int n</FONT>
<BR><FONT SIZE=2>places spce for an int on the stack, and you tell scanf</FONT>
<BR><FONT SIZE=2>to place the int in it. Fine.</FONT>
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<P><FONT SIZE=2>char *str</FONT>
<BR><FONT SIZE=2>places spaces for a pointer to character on the stack.</FONT>
<BR><FONT SIZE=2>However, you don't tell scanf to place its data in it</FONT>
<BR><FONT SIZE=2>(you lack the &), but where it's pointing to. And you</FONT>
<BR><FONT SIZE=2>haven't made it point anywhere, so it's pointing ...</FONT>
<BR><FONT SIZE=2>somewhere unknown.</FONT>
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<P><FONT SIZE=2>- char *str,*str1;</FONT>
<BR><FONT SIZE=2>+ char str[256],str1[256];</FONT>
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<P><FONT SIZE=2>or</FONT>
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<P><FONT SIZE=2>- char *str,*str1;</FONT>
<BR><FONT SIZE=2>+ char *str=malloc(256),*str1=malloc(256);</FONT>
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<P><FONT SIZE=2>However, remember than with scanf, you can't (AFAIK) size</FONT>
<BR><FONT SIZE=2>the allocated memory to what is read, thus, stack smashing</FONT>
<BR><FONT SIZE=2>possibility in the first patch, and arena corruption in</FONT>
<BR><FONT SIZE=2>the second. A safer way is to read little bits by little</FONT>
<BR><FONT SIZE=2>bits (of known size) and allocate accordingly.</FONT>
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<P><FONT SIZE=2>--</FONT>
<BR><FONT SIZE=2>Vincent Penquerc'h </FONT>
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