c语言之IO使用文件分割

#include 
#include    // ceil()
#include  // exit()
//cl filesplit.c
int main(int argc, char *argv[]) {
    char part_filename[200];
    FILE *ptr_source, *ptr_part;
    size_t parts, i;
    unsigned long int part_size, written_bytes;
    int byte;
    if (argc != 3) {
        printf("Usage: %s  \n", argv[0]);
        exit(1);
    }

    if ((ptr_source = fopen(argv[2], "rb")) == NULL) {
        perror("Could not open file to split");
        exit(1);
    }

    fseek(ptr_source, 0, SEEK_END);
    part_size = atol(argv[1]) * 1024 * 1024;
    if (part_size == 0) {
        printf("Invalid part size: %s\n", argv[1]);
        exit(1);
    }
    parts = (size_t) ceil((double) ftell(ptr_source) / part_size);
    rewind(ptr_source);
    printf("File will be split into %u parts.\n", parts);

    for (i = 0; i < parts; i++) {
        printf("\nWriting part%02d... ", i);
        sprintf(part_filename, "%s.part%02d", argv[2], i);

        if ((ptr_part = fopen(part_filename, "wb")) == NULL) {
            perror("Could not open part for writing");
            exit(1);
        }
        for (written_bytes = 0; written_bytes < part_size &&
            (byte = fgetc(ptr_source)) != EOF; written_bytes++)
        {
            fputc(byte, ptr_part);
        }

        printf("(%lu bytes)", written_bytes);
        fclose(ptr_part);
    }
    printf("\n\nDone!\n");
    fclose(ptr_source);
    return 0;
}