Append to the end of a file in C

c file append fseek
Sonofblip picture Sonofblip · Oct 17, 2013 · Viewed 187.2k times · Source

I'm trying to append the contents of a file myfile.txt to the end of a second file myfile2.txt in c. I can copy the contents, but I can't find a way to append. Here's my code:

FILE *pFile;
FILE *pFile2;
char buffer[256];

pFile=fopen("myfile.txt", "r");
pFile2=fopen("myfile2.txt", r+);
if(pFile==NULL) {
    perror("Error opening file.");
}
else {
    while(!feof(pFile)) {
        if(fgets(buffer, 100, pFile) != NULL) {
        fseek(pFile2, -100, SEEK_END);
        fprintf(pFile2, buffer);
    }
}
fclose(pFile);
fclose(pFile2);

I don't think I'm using fseek correctly, but what I'm trying to do is call fseek to put the pointer at the end of the file, then write at the location of that pointer, instead of at the beginning of the file. Is this the right approach?

Answer

cdarke picture cdarke · Oct 17, 2013

Open with append:

pFile2 = fopen("myfile2.txt", "a");

then just write to pFile2, no need to fseek().

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