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[alexandertnt]

How do I memcmp? I am trying to make a program that goes through a binary file and finds a given value.

Code: [Select]

unsigned long searchData = 0;
for(int i = 0; i < file.uncompressedSize-3; i++)
{
if (!memcmp(&searchData, file.uncompressedData + i, 4));
{
fwrite(&searchData, 4,1, stderr);
fprintf(stderr, "|");
fwrite(file.uncompressedData + i, 1,4, stderr);
fprintf(stderr, "\n");
}
}

writes (as shown in notepad++)


Which are clearly not equal

[RulerOfNothing]

      if (!memcmp(&searchData, file.uncompressedData + i, 4));
should not have the semicolon at the end (because this is a null statement, meaning that the subsequent block is always executed)

[Telgin]

Out of curiosity, what compiler are you using and what warning level?  I would hope that most compilers would have some kind of warning for that.  I've seen that mistake a few times on loops, which leads to quite frustrating debugging to say the least.

[alexandertnt]

      if (!memcmp(&searchData, file.uncompressedData + i, 4));
should not have the semicolon at the end (because this is a null statement, meaning that the subsequent block is always executed)

...
Awww damn it, that fixed it.
(how did I miss that )

Out of curiosity, what compiler are you using and what warning level?  I would hope that most compilers would have some kind of warning for that.  I've seen that mistake a few times on loops, which leads to quite frustrating debugging to say the least.

Code: [Select]

g++ fileutil.cpp -std=c++11

with cygwin. It would be great if there was at least a warning for something like that.

[Telgin]

Hmm, no idea what warning level g++ assumes, but I think there's a option call -wall that increases the warning level.  I'd test it here but I'm on Windows without Cygwin.

Actually, I checked and found this: advice on gcc / g++ flags.

[Maklak]

With gcc I generally use --Wall --Wextra

[tuypo1]

i realized i know a pitifully small amount about programing so i picked up a copy of learning web app development from the libary

[Mephisto]

i realized i know a pitifully small amount about programing so i picked up a copy of learning web app development from the libary

Node, Redis, Mongo, CloudFoundry. That's basically Buzz Words: Let's Learn Them.

I don't know if I would inflict Node on anyone who is just starting out. Maybe start with the basics of programming.

[tuypo1]

i realized i know a pitifully small amount about programing so i picked up a copy of learning web app development from the libary

Node, Redis, Mongo, CloudFoundry. That's basically Buzz Words: Let's Learn Them.

I don't know if I would inflict Node on anyone who is just starting out. Maybe start with the basics of programming.

i do know the basics and the books all javascript

[Mephisto]

... the books all javascript

If this is the book you picked up, the buzz words don't start up until later. I guess it's not a bad book to use.

[tuypo1]

... the books all javascript

If this is the book you picked up, the buzz words don't start up until later. I guess it's not a bad book to use.

yep thats the one do you have any idea why the hell they put that on the cover

[EnigmaticHat]

In my experience a lot of books about programming assume you already know things about programming.  The target audience seems to be people who already know one language and want to learn another.

Of course that experience is from ~7 years ago.

http://www.codecademy.com/ can teach several languages and helped me a good amount with Python.  The main lessons only cover the basics though.

[tuypo1]

In my experience a lot of books about programming assume you already know things about programming.  The target audience seems to be people who already know one language and want to learn another.

Of course that experience is from ~7 years ago.

http://www.codecademy.com/ can teach several languages and helped me a good amount with Python.  The main lessons only cover the basics though.

it does assume a basic knowledge of things like if, else ,loops and other things which i do have but other then that it assumes no knowladge

i will probably go on that website anyway as the preface does mention it its a pretty new book

[Rose]

... the books all javascript

If this is the book you picked up, the buzz words don't start up until later. I guess it's not a bad book to use.

yep thats the one do you have any idea why the hell they put that on the cover

Because Gnu.

Also, today I learned the evils of static.

[Arx]

In my experience a lot of books about programming assume you already know things about programming.  The target audience seems to be people who already know one language and want to learn another.

Of course that experience is from ~7 years ago.

http://www.codecademy.com/ can teach several languages and helped me a good amount with Python.  The main lessons only cover the basics though.

it does assume a basic knowledge of things like if, else ,loops and other things which i do have but other then that it assumes no knowladge

i will probably go on that website anyway as the preface does mention it its a pretty new book

How to Think Like a Computer Scientist is solid for learning Python, Java, or (I think) C++. I don't think there's a Javascript version, though.