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strtol will convert your string to a 32 bit value:<br />
&quot;1111111111&quot; -&gt; 00000000000000000000001111<wbr />111111 -&gt; 1023<br />
<br />
you need:<br />
11111111111111111111111111<wbr />111111 -&gt; -1<br />
<br />
bit 10 of your string indicates whether you have a signed or unsigned value:<br />
with the mask 0x200 you can check if this bit is set or not <br />
if (dnum &amp;&nbsp;0x200)<br />
<br />
if so, you have to overwrite all the zeros with ones<br />
dnum |= 0xfffffc00
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strtol will convert your string to a 32 bit value:
"1111111111" -> 00000000000000000000001111111111 -> 1023

you need:
11111111111111111111111111111111 -> -1

bit 10 of your string indicates whether you have a signed or unsigned value:
with the mask 0x200 you can check if this bit is set or not
if (dnum & 0x200)

if so, you have to overwrite all the zeros with ones
dnum |= 0xfffffc00

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Excellent, worked like a charm. &nbsp;Thanks chip3d
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Excellent, worked like a charm.  Thanks chip3d

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<div class="content wysiwyg-content">
I have a program that receives a string in binary format. &nbsp;The string is a signed binary number between -511 and 512. &nbsp;I need to convert the string into an int to perform some mathmatical operations on it. &nbsp;I used the strtol function to convert the string, but it always treats the 10 binary digits as unsigned. &nbsp;How do I convert the binary string so that it is signed?<br />
<br />
All strings are 10 characters long, consisting of only a 1 or a 0. ie. &quot;1111111111&quot; should be converted to -1, not 1023.<br />
<br />
I have<br />
int conv (string bnum) {<br />
&nbsp; &nbsp; &nbsp;int dnum = strtol(bnum.c_str(),&amp;pEnd,<wbr />2);<br />
&nbsp; &nbsp; &nbsp;return dnum;<br />
}<br />
<br />
But it's not working, HELP!!!
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I have a program that receives a string in binary format.  The string is a signed binary number between -511 and 512.  I need to convert the string into an int to perform some mathmatical operations on it.  I used the strtol function to convert the string, but it always treats the 10 binary digits as unsigned.  How do I convert the binary string so that it is signed?

All strings are 10 characters long, consisting of only a 1 or a 0. ie. "1111111111" should be converted to -1, not 1023.

I have
int conv (string bnum) {
     int dnum = strtol(bnum.c_str(),&pEnd,2);
     return dnum;
}

But it's not working, HELP!!!

Convert binary string to decimal, strtol()

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