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reading a text file and searching for a sentence

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Re: reading a text file and searching for a sentence

#11

Dec 25th, 2007

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Originally Posted by Ancient Dragon

line 6: do you have a program on your computer called command.exe ? If not then that line of code will do nothing other than get an error message from the operating system that "command not found".

lines 8 and 10: that loop doesn't work right. You need to combine them like this:
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C++ Syntax (Toggle Plain Text)
while( file_op.getline(str,5000) )
{
    // compare the strings here to see if this line is the one you are looking for
}
while( file_op.getline(str,5000) ) { // compare the strings here to see if this line is the one you are looking for }
line 13: you can not compare two c-style character arrays like that. Use strcpy() to do that
if( strcpy(errorline, str) == 0)

thanks dragon but i tried comparing the strings with a strcmp() function and it won't work

this is what happens, if the txt file was created by the running program this way
system("somecommand>output.txt") then comparing the strings with a strcmp() function doesn't work [meaning that when the two compared strings do actually match, the program always decides that they don't match]

but if i created the file myself and typed in it whatever i want to be compared, then strcmp() function would work.

Last edited by hashinclude; Dec 25th, 2007 at 10:56 am.

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Re: reading a text file and searching for a sentence

#12

Dec 25th, 2007

The code you posted a week ago is obviously not the same code you are using today. So post code (I can't see your monitor very well) and zip up the data file and post it too. stramp is case sensitive so maybe the string that's in the data file is not the same case as the string you want to compare. To do a case-insensive compare you can convert both strings to either upper or lower case before calling strcmp(). Some compilers have a case-insensitive compare function, such as stricmp() in Microsoft compilers and compareNoCase() (or something like that) in some other compilers.

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Re: reading a text file and searching for a sentence

#13

Dec 26th, 2007

hi dragon, sorry for the late reply

here's my code

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	char str[5000];
                system("mycommand>output.exe");
	char error[]="the error line to be checked";
	fstream file_op("output.txt",ios::in);
 
	while( file_op.getline(str,5000) )
 
	{
		cout<<str<<endl;
		if(strcmp(error,str) == 0)
                                    {
                                          getchar();
                                     }         
	{
	char str[5000];
                system("mycommand>output.exe");
	char error[]="the error line to be checked";
	fstream file_op("output.txt",ios::in);

	while( file_op.getline(str,5000) )

	{
		cout<<str<<endl;
		if(strcmp(error,str) == 0)
                                    {
                                          getchar();
                                     }         
	{

the code compiles with no errors and the program runs with no errors , but the issue here is that strcmp(error,str) always returns a value other than zero even if the lines compared match up !

whats confusing is that when i create the output.txt file manually and not by having it created using the system("mycommand>output.exe") function and then type in the the same output i would get from mycommand.exe , the strcmp(error,str) would then detect the matching lines properly!

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Re: reading a text file and searching for a sentence

#14

Dec 30th, 2007

tanks a lot

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Re: reading a text file and searching for a sentence

#15

Dec 31st, 2007

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Originally Posted by az1983us

tanks a lot

for what ?

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Re: reading a text file and searching for a sentence

#16

Dec 31st, 2007

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Originally Posted by hashinclude

whats confusing is that when i create the output.txt file manually and not by having it created using the system("mycommand>output.exe") function and then type in the the same output i would get from mycommand.exe , the strcmp(error,str) would then detect the matching lines properly!

That indicates the text generated by the system() function is not the same as what you type manually, could be as simple as a space, tab character, or capitalization. Load both files up into Notepad and compare them side-by-side to see what are the differences.

Don't PM me with questions -- you might get a nasty PM in response. If you have a question then post it in one of the forums.

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Re: reading a text file and searching for a sentence

#17

Jan 1st, 2008

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Originally Posted by Ancient Dragon

That indicates the text generated by the system() function is not the same as what you type manually, could be as simple as a space, tab character, or capitalization. Load both files up into Notepad and compare them side-by-side to see what are the differences.

although they look identical in notepad , i believe like you said, a space or tab character is added somewhere on each line by the system() function.
i tried removing spaces from the line created by the system() function and then using strcmp() but it still didn't work :/

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Re: reading a text file and searching for a sentence

#18

Jan 1st, 2008

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Originally Posted by hashinclude

although they look identical in notepad , i believe like you said, a space or tab character is added somewhere on each line by the system() function.
i tried removing spaces from the line created by the system() function and then using strcmp() but it still didn't work :/

Then that obviously wasn't the problem. What I'd do now is display every character entered in hex just before comparing and, as AD suggests, see if there are differences you can't see.

You also might want to post part of the file.

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Re: reading a text file and searching for a sentence

#19

Jan 1st, 2008

ok here is something i have tried :

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	char str[500];
	char error[]="Windows IP Configuration"; //error string to find
	system("ipconfig>output.txt");
	fstream file("output.txt",ios::in);
 
	int i=0,l=1,counter=0;
 
	while( file.getline(str,500) )
	{
	   cout<<"\nLine #"<<l<<":\n\n";
 
	    while(str[i]==error[i])
	     {
	       cout<<"[ "<<str[i]<<" ]"<<" = "<<"[ "<<error[i]<<" ]\n";	
	       i++;
	       counter++;				
	      }
 
	     if(strcmp(error,str)==0 || counter==24)
	      {
		cout<<"\nerror found!\n";cin.ignore();
	       }
 
	      i=0;l++;counter=0;
	  }
          file.close();
          return 0;
	char str[500];
	char error[]="Windows IP Configuration"; //error string to find
	system("ipconfig>output.txt");
	fstream file("output.txt",ios::in);
	
	int i=0,l=1,counter=0;
	
	while( file.getline(str,500) )
	{
	   cout<<"\nLine #"<<l<<":\n\n";

	    while(str[i]==error[i])
	     {
	       cout<<"[ "<<str[i]<<" ]"<<" = "<<"[ "<<error[i]<<" ]\n";	
	       i++;
	       counter++;				
	      }

	     if(strcmp(error,str)==0 || counter==24)
	      {
		cout<<"\nerror found!\n";cin.ignore();
	       }

	      i=0;l++;counter=0;
	  }
          file.close();
          return 0;

and this is the output:

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 C++ Syntax (Toggle Plain Text) 
Line #1:
 
 
Line #2:
 
[ W ] = [ W ]
[ i ] = [ i ]
[ n ] = [ n ]
[ d ] = [ d ]
[ o ] = [ o ]
[ w ] = [ w ]
[ s ] = [ s ]
[   ] = [   ]
[ I ] = [ I ]
[ P ] = [ P ]
[   ] = [   ]
[ C ] = [ C ]
[ o ] = [ o ]
[ n ] = [ n ]
[ f ] = [ f ]
[ i ] = [ i ]
[ g ] = [ g ]
[ u ] = [ u ]
[ r ] = [ r ]
[ a ] = [ a ]
[ t ] = [ t ]
[ i ] = [ i ]
[ o ] = [ o ]
[ n ] = [ n ]
 
error found!
Line #1:


Line #2:

[ W ] = [ W ]
[ i ] = [ i ]
[ n ] = [ n ]
[ d ] = [ d ]
[ o ] = [ o ]
[ w ] = [ w ]
[ s ] = [ s ]
[   ] = [   ]
[ I ] = [ I ]
[ P ] = [ P ]
[   ] = [   ]
[ C ] = [ C ]
[ o ] = [ o ]
[ n ] = [ n ]
[ f ] = [ f ]
[ i ] = [ i ]
[ g ] = [ g ]
[ u ] = [ u ]
[ r ] = [ r ]
[ a ] = [ a ]
[ t ] = [ t ]
[ i ] = [ i ]
[ o ] = [ o ]
[ n ] = [ n ]

error found!

you notice the first line in the file is an empty space
now the reason my error was found in the second line is because of the counter inside the if(!strcmp(error,str)||counter==24) statement even though you can see how the line and the error string match perfectly, !strcmp(error,str) still didn't see it O_O

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Re: reading a text file and searching for a sentence

#20

Jan 1st, 2008

Maybe you need to change:-

cout<<"\nerror found!\n";cin.ignore();

to

cout<<"\nMatch!\n";cin.ignore();

Or alternatively change:-

if(strcmp(error,str)==0

to

if(strcmp(error,str)==1

The choice is yours.

Last edited by iamthwee; Jan 1st, 2008 at 3:39 pm.

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