Thread: Question on strings

Hi,

I'm a begginer in C (learning it for fun) and I have a question regarding strings.

I programmed a simple 'extractor' for a file format and I want each of my files to be named sequentially as FILE00.ext, FILE01.ext, etc.

Here is the code snippet that write the files:

Code:

for (i = 0; i < num_of_files; i++)   {
    
    fseek(input, (file_offset[i] + start_offset), SEEK_SET);
    
    FILE *ripped_file = fopen( filename , "w+b"); 
    
    for ( j = 0; j < ( file_offset[i+1] - file_offset[i] ); j++)    {
        
        ch = getc(input);
        putc(ch, ripped_file);
        
        }
    
    fclose(ripped_file);
    
    }

Everything works fine, but how can I make the "filename" be incremented each time? I thought of doing some like counter++ (with an integer) but I'm not sure how can I append that to the filename. Can someone give an actual example of this?

Code:

....
char filename[10]; //the name, like FILE in your example, or anything else you would like
char varStr[7]; // the number followed by .ext
char newFilename[17]; //the filename you want

...

strcpy(varStr, "00.ext");  //varStr is "00.ext"
newFilename = strcat(filename, varStr); //this appends the varStr to the filename

...
//This creates FILE00.ext, FILE01.ext etc etc
FILE * fd[5];
for (int i=0; i<5; ++i) {   
   newFilename = strcat(filename, varStr);
   fd[i] = fopen(newFilename, "w");
   varStr[1]++;
}

Notice that varStr[1] = '0' at the beggining. If you increase it it will be '1' (not 1, but the char '1'). And so on. At the tenth file of course you have to set varStr[1] = '0' and varStr[0] = '1'. Last note, every string is null-terminated. If you make that sure then it should work for a size less than the maximum size of the array