You could just add a decimal to either the numerator or the denominator:
double result = 30.0 / 233;
double result = 30 / 233.0;
Typecasting either of the two numbers also works.
As for the second part of the question, if you use printf-style format strings, you can do something like this:
sprintf(str, "result = %.2f", result);
Bascially, the ".2" represents how many digits to output after the decimal point.
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