Objective

Implement a function that returns the absolute value of an int as a long, widening the value before it ever negates it.

Steps

• n is any int, anywhere from INT_MIN to INT_MAX. Return its absolute value.
• A value that is already zero or positive comes back unchanged. A negative value comes back with its sign dropped.
• Negating an int that holds INT_MIN is undefined behavior. The mathematical result is 2147483648, one past the top of the int range, so the standard says nothing about what happens and the compiler is free to keep the value negative, wrap it, or drop the expression. Never write -n while n is still an int.
• Cast to long first, then negate the long. That is the whole reason the return type is long: abs_safe(INT_MIN) must return 2147483648, which no int can hold.
• Order matters and only one order works. Widening after the negation, as in (long)(-n), has already run the undefined operation before the cast happens.
• Every other input fits in an int, so abs_safe(INT_MAX) returns 2147483647 and abs_safe(0) returns 0.
• INT_MIN and INT_MAX come from <limits.h>. You may call nothing, so abs and labs are out.
• The tests print your return value with %ld followed by a newline.

Objective

Implement a function that returns the absolute value of an int as a long, widening the value before it ever negates it.

Steps

• n is any int, anywhere from INT_MIN to INT_MAX. Return its absolute value.
• A value that is already zero or positive comes back unchanged. A negative value comes back with its sign dropped.
• Negating an int that holds INT_MIN is undefined behavior. The mathematical result is 2147483648, one past the top of the int range, so the standard says nothing about what happens and the compiler is free to keep the value negative, wrap it, or drop the expression. Never write -n while n is still an int.
• Cast to long first, then negate the long. That is the whole reason the return type is long: abs_safe(INT_MIN) must return 2147483648, which no int can hold.
• Order matters and only one order works. Widening after the negation, as in (long)(-n), has already run the undefined operation before the cast happens.
• Every other input fits in an int, so abs_safe(INT_MAX) returns 2147483647 and abs_safe(0) returns 0.
• INT_MIN and INT_MAX come from <limits.h>. You may call nothing, so abs and labs are out.
• The tests print your return value with %ld followed by a newline.