[C] Incremental string updates - 00001.png 00002.png etc - Tilted Forum Project Discussion Community

Jakejake · 07-18-2005, 10:52 AM

Hi,
I am writing a program in C that will be outputting a lot of files that I want to be named 00001.png 00002.png 00003.png and so on.

The way I am doing it at the moment is as follows:

Code:

        for(i=0; i < 10000; i++)
        {
                filename[4]++;
                if(filename[4] > 57)
                {
                        filename[4] = 48;
                        filename[3]++;
                        if(filename[3] > 57)
                        {
                                filename[3] = 48;
                                filename[2]++;
                                if(filename[2] > 57)
                                {
                                        filename[2] = 48;
                                        filename[1]++;
                                        if(filename[1] > 57)
                                        {
                                                filename[1]++;
                                        }
                                }
                        }
                }
                //CODE THAT WRITES TO FILE USING filename
        }

Now this seems a rather ugly way to do it. What I should be doing is simply incrementing an integer and then converting that to a string somehow, but I can't work out how to do this.

Any ideas?

Thanks

Robbie

hrdwareguy · 07-18-2005, 12:18 PM

You could do something like this:

Code:

string:filename;
for i=1 to 10000
{
  filename=IntToStr(i)+.PNG;
  while length(filename) < 12 filename='0'+filename;
  //write file here
}

where 12 is whatever lenght you want to give the filename including the .PNG extension.

feelgood · 07-18-2005, 12:27 PM

Never mind, was thinking in Java, not C

Anomaly_ · 07-18-2005, 12:42 PM

In C you could do something like this:

Code:

int num = 0;
char fileName[5];
  
int i;
for(i = 0; i <= 10000; i++)
{
  sprintf(fileName, "%05d", num);
  // Append file extension to fileName and write it
  num++;		
}

billys · 07-18-2005, 12:43 PM

My C is a bit rusty but sprintf is your friend here.

Try:

Code:

char buffer[10];
for(int i=0; i<10000; i++) {
  sprintf(buffer, "%05d.png", i);
  /* write file contents */
}

the %05d is a format string that tells the compiler to format a string containing a decimal integer (the d) to a width of 5 characters (the 5) and to pad using a 0 character (the 0) and then to append that with .png.

I dont have a C compiler anymore so I cant test this but it should be right, google will find you literally hundreds of guides to format strings with printf and sprintf though.

Hope this helps

billys · 07-18-2005, 12:45 PM

beaten by a minute

I guess it confirms that the %05d was right though, i wasnt sure

Jakejake · 07-18-2005, 01:19 PM

Thanks guys. The sprintf() command worked great.

07-18-2005, 10:52 AM	#1 (permalink)
Jakejake Crazy	[C] Incremental string updates - 00001.png 00002.png etc Hi, I am writing a program in C that will be outputting a lot of files that I want to be named 00001.png 00002.png 00003.png and so on. The way I am doing it at the moment is as follows: Code: for(i=0; i < 10000; i++) { filename[4]++; if(filename[4] > 57) { filename[4] = 48; filename[3]++; if(filename[3] > 57) { filename[3] = 48; filename[2]++; if(filename[2] > 57) { filename[2] = 48; filename[1]++; if(filename[1] > 57) { filename[1]++; } } } } //CODE THAT WRITES TO FILE USING filename } Now this seems a rather ugly way to do it. What I should be doing is simply incrementing an integer and then converting that to a string somehow, but I can't work out how to do this. Any ideas? Thanks Robbie Last edited by Jakejake; 07-18-2005 at 10:52 AM.. Reason: typo

07-18-2005, 12:18 PM	#2 (permalink)
hrdwareguy "Officer, I was in fear for my life" Location: Oklahoma City	You could do something like this: Code: string:filename; for i=1 to 10000 { filename=IntToStr(i)+.PNG; while length(filename) < 12 filename='0'+filename; //write file here } where 12 is whatever lenght you want to give the filename including the .PNG extension. __________________ Gun Control is hitting what you aim at Aim for the TFP, Donate Today

07-18-2005, 12:27 PM	#3 (permalink)
feelgood Free Mars! Location: I dunno, there's white people around me saying "eh" all the time	Never mind, was thinking in Java, not C __________________ Looking out the window, that's an act of war. Staring at my shoes, that's an act of war. Committing an act of war? Oh you better believe that's an act of war

07-18-2005, 12:42 PM	#4 (permalink)
Anomaly_ Insane	In C you could do something like this: Code: int num = 0; char fileName[5]; int i; for(i = 0; i <= 10000; i++) { sprintf(fileName, "%05d", num); // Append file extension to fileName and write it num++; }

07-18-2005, 12:43 PM	#5 (permalink)
billys Upright Location: Chester, UK	My C is a bit rusty but sprintf is your friend here. Try: Code: char buffer[10]; for(int i=0; i<10000; i++) { sprintf(buffer, "%05d.png", i); /* write file contents */ } the %05d is a format string that tells the compiler to format a string containing a decimal integer (the d) to a width of 5 characters (the 5) and to pad using a 0 character (the 0) and then to append that with .png. I dont have a C compiler anymore so I cant test this but it should be right, google will find you literally hundreds of guides to format strings with printf and sprintf though. Hope this helps

07-18-2005, 12:45 PM	#6 (permalink)
billys Upright Location: Chester, UK	beaten by a minute I guess it confirms that the %05d was right though, i wasnt sure

07-18-2005, 01:19 PM	#7 (permalink)
Jakejake Crazy	Thanks guys. The sprintf() command worked great.