In computer programming, redundant code is source code or compiled code in a computer program that is unnecessary, such as:
A NOP instruction might be considered to be redundant code that has been explicitly inserted to pad out the instruction stream or introduce a time delay, for example to create a timing loop by "wasting time". Identifiers that are declared, but never referenced, are termed redundant declarations.
The following examples are in C.
The second iX*2 expression is redundant code and can be replaced by a reference to the variable iY. Alternatively, the definition int iY = iX*2 can instead be removed.
Consider:
int shorter_magnitude(int u1, int v1, int u2, int v2)
As a consequence of using the C preprocessor, the compiler will only see the expanded form:
Because the use of min/max macros is very common, modern compilers are programmed to recognize and eliminate redundancy caused by their use.
There is no redundancy, however, in the following code:
int random(int cutoff, int range)
If the initial call to rand, modulo range, is greater than or equal to cutoff, rand will be called a second time for a second computation of rand%range, which may result in a value that is actually lower than the cutoff. The max macro thus may not produce the intended behavior for this function.