Thread: Couple Of Questions I'm Absolutly Stuck On

Hey,

ok lets start with the one your going to find dead easy.

i am trying to assign a string to this char array over multiple lines however I cannot work out the syntax

Code:

char buffer[500];
buffer = "\n |-------------------------------------------------------|
_ \n | Algorithem        | Time    | Comparisons | Swaps     | 
_ \n |-------------------------------------------------------|";

2nd question is redarding file access....
I am trying to create a new text file for logging purposes each time the program runs. So i thought the time would be a nice almost unique filename to have.....again cannot get it to go. Here is the code I have so far.

Code:

out=fopen(asctime(time(NULL)) + ".txt","w");

I'm guessing both are just me not access the char arrays (strings) propperly.

Thanks for your help in advance.

Chris

1. With long strings like these declare it on multiple lines by typing \ and then [enter].

Code:

buffer = "\n |-------------------------------------------------------| \
 		_ \n | Algorithem        | Time    | Comparisons | Swaps     |  \
		_ \n |-------------------------------------------------------|";

2. Strings do not concatenate with plus in C, use the strncat function.

Code:

out = fopen( strncat(asctime(time(NULL)), ".txt", 4), "w" );

Adjacent string literals are concatenated.

Code:

char buffer[500] = "\n |-------------------------------------------------------|"
                   "_ \n | Algorithem        | Time    | Comparisons | Swaps     | "
                   "_ \n |-------------------------------------------------------|";

[edit]Note that this and citizen's version are different -- the leading whitespace in citizen's is significant.

Originally Posted by citizen

2. Strings do not concatenate with plus in C, use the strncat function.

Code:

out = fopen( strncat(asctime(time(NULL)), ".txt", 4), "w" );

I don't think it's a very good idea to concatenate to a static buffer that is part of the standard library and likely has a size fixed exactly for the intended output only.

Thanks guys,

I got it accepting the multi lined string as far as i know but now its saying lvalue required

Code:

void printHeader( FILE * filePointer ) {
	char buffer[500];

	buffer = "\n |-------------------------------------------------------|"
		"\n | Algorithem        | Time    | Comparisons | Swaps     |"
		"\n |-------------------------------------------------------|";
	
	printf( "%s", buffer );
	fprintf( filePointer, "%s" );
}

Thanks for the quick reply before

Chris

Note that my version uses an initialization. Your uses assignment. You cannot assign an array, but you can initialize it. That is,

Code:

char buffer[500] = "\n |-------------------------------------------------------|"
		"\n | Algorithem        | Time    | Comparisons | Swaps     |"
		"\n |-------------------------------------------------------|";

thanks for your help guys, I have sorted them problems and now encountered some more, I will try and work them out before posting again.

cheers

Code:

fprintf( filePointer, "%s" );

You forgot to supply a parameter here.


[Why put the newline at the beginning? I've never understood that. Put the end of the line at the end of the line...]

well spotted, i hadn't noticed and nor did borland.

the new line at the begining is just to drop it down so when it outputs in dos its not right at the top of the screen. other languages I like to put it at the end. I agree it causes less problems there, but not too much of a problem for this program.