Converting minutes to seconds in C?

You can emulate the behaviour of floor using integer division.

Code:

	float input = 50.429;
	int m = input / 1;
	int s = ((input - m) * 60) / 1;
	printf("%d %d", m, s);

Look up "integer division" in C for details.

 

Some tips:
Scanf is a shitty function prone to all sorts of unintended behaviour. You are much better off capturing the input into a buffer then using sscanf. In this case the input is so simple that not much can go wrong, but it's good practice all the same.

For an overflow-safe read from STDIN use fgets:

As the manpage says, the fgets function will behave as a read function should: reading up to the number of chars specified, a new line char or EOF, which ever comes first. The function also provides a return value indicating the success of the read. If the read fails (i.e. EOF has been reached or broken pipe etc.) then it returns null.

You should also note that all scanf functions return the number of elements in the format string that they successfully scanned. So for example if you had "%f %f %f" but your input string was "50.0 5.1" then it would return 2.

So for example (untested):

Code:

char buffer[51];
if (fgets(buffer, 50, stdin)) {
    float x = 0;
    if (sscanf(buffer, "%f", &x) == 1) {
        // float was read from input do calcs here
    } else {
        fprintf(stderr, "input did not contain a float\n");
    }
} else {
    fprintf(stderr, "read from stdin failed\n");
}