How do I split a text file into parts in C?

Question

Suppose I have a text file that says: This file has plain text

Now, I want to divide this text file into 'n' number of parts with equal characters. Suppose the user wants three divisions, then 1.txt, 2.txt and 3.txt should be created, with about 8 characters each.

(The next part of this program is to rejoin these files back into the original state but I'm sure I'll be able to do that myself If I can get help with this first part).

Can you guys guide me in this matter?

Language used is C.

void main(int argc, char** argv)
{
int iChunkNo=0;
char cFileName[30];

iChunkNo = atoi(argv[2]);
strcpy(cFileName, argv[1]);

printf("The file will be divided into %d chunks \n", iChunkNo);

FILE* file_read_pointer;
file_read_pointer = fopen(cFileName, "r");

int iCount=0;
char ch;

while (1) 
{
        ch = fgetc(file_read_pointer);
        if (ch == EOF)
            break;
        ++iCount;
}

printf("The number of characters in the file is: %d \n", iCount);   

int iCharPerFile = 0;
iCharPerFile = iCount/iChunkNo;

printf("The number of characters per chunk file will be: %d \n", iCharPerFile);

FILE* file_write_pointer;   

int j=1;
for(j; j<=iChunkNo; j++)
{   
    char num[5] = {j};
    char ext[4] = {"txt"};

    char name[15];
    sprintf(name, "%d.%s", j, ext);     

    FILE* file_write_pointer;
    file_write_pointer = fopen(name, "w");
}

int i=0;

for(i; i<iCharPerFile; i++)
{
    char temp;
    temp = fgetc(file_read_pointer);
    //fputc(temp, file_write_pointer);
    fprintf(file_write_pointer, "%c", temp);
}
}

Answer 1

You could do something like this:

• Find the size of the file (using fseek and ftell). Then seek back to the beginning
• Determine the size you need to write to each file (size / n)
• Read one character at a time (use getc) and write to the corresponding file (putc)
  • Use sprintf(fname, "%d.txt", index) to build names like "1.txt"
  • Use fopen to open files and keep a FILE *current to which you write at each step

That being said, you should start slow. First make a program that simply copies one file into another using getc + putc and work your way up.