You will have to use a cascade of if's (also/especially if your value is a floating point number)
int value= ...;
if (value>=0 && value<=250 {
// some code 0..250
}
else
if (value>250 && value<=500) {
// some code 251..500
}
else
if (value>500 && value<=1000) {
// etc.
}
else {
// all other values (less than zero or 1001...)
}