Printing fizzy lines

Challenge

Given a test case print out a FizzBuzz Series.
Specifications

• The first argument is a path to a file.

• Each line includes a test case.

• Each test case is comprised of three spaced delimited integers.

• The first two integers are the dividers X and Y.

• The third integer, N is how far to count.

• Print out the series 1 through N, replacing numbers divisible by X with F, numbers divisible by Y with B and numbers divisible by both with FB.

Constraints

• The input file is formatted correctly.

• The numbers are valid positive integers.

• X is in range [1, 20]

• Y is in range [1, 20]

• N is in range [21, 100]

• Output should be one line per set with no trailing or empty spaces.

Input Sample

3 5 10

2 7 15

Output Sample

1 2 F 4 B F 7 8 F B

1 F 3 F 5 F B F 9 F 11 F 13 FB 15

Source

My Solution:

#include 

void print_buzzified(int fizz, int buzz, int count) {
    for (int i = 1; i <= count; i++) {
        if (i % fizz == 0 && i % buzz == 0) {
            printf("%s", "FB");
        } else if (i % fizz == 0) {
            printf("%s", "F");
        } else if (i % buzz == 0) {
            printf("%s", "B");
        } else {
            printf("%d", i);
        }

        printf(i < count ? " " : "\n");
    }
}

int main(int argc, const char * argv[]) {
    FILE *file;
    if (argc < 2 || !(file = fopen(argv[1], "r"))) {
        puts("No argument provided / File not found.");
        return 1;
    }

    file = fopen(argv[1], "r");
    int fizz;
    int buzz;
    int count;

    while (!feof(file)) {
        fscanf(file, "%d %d %d", &fizz, &buzz, &count);
        print_buzzified(fizz, buzz, count);
    }

    fclose(file);
}

Design:

-
Good job on setting up everything in main(), then passing off control to another function.

-
Declare and initialize file after checking the command line arguments.

-
Initialize fizz, buzz, and count.

-
Don't use !feof(file) to control your loop. See this answer for more details.

-
Check the return value of fscanf() to make sure we're reading good data.

-
Good job remembering to close the file.

Readability & Maintainability/Performance

I'm grouping these two categories together for this review, since they happen to go hand in hand.

-
Your for loop can be refactored down a bit:

if (i % fizz == 0) fputc('F', stdout);
if (i % buzz == 0) fputc('B', stdout);
if (i % fizz && i % buzz)) fprintf(stdout, "%d", i);

Some people may find issue with the duplicated check on i with fizz and buzz, but we cut out some conditional branches doing this and the more branches we cut, the less susceptible to branch prediction we are. There may be a better way to write this, but I can't think of it right now.

-
Note how I used fputs() and fputc() in the code above instead of printf(). This is because those functions are \$ O(1) \$ operations instead of \$ O(n) \$ to loop over the string and format it. This may speed up your program by a hair, if that, but the main reason I recommend this change is to make clear we aren't modifying any strings.

-
Since the range of \$ X \$, \$ Y \$, and \$ N \$ is 1-20, it would be good to change the type representing these variables to something a bit more compact in memory.

Depending on what we want to optimize for (memory or performance), I would recommend either uint_least8_t or uint_fast8_t.

-
uint_least8_t: give me the smallest type of unsigned int which has at least 8 bits. Optimize for memory consumption.

-
uint_fast8_t: give me an unsigned int of at least 8 bits. Pick a larger type if it will make my program faster, because of alignment considerations. Optimize for speed.

StackExchange Code Review Q#132307, answer score: 8