Swap (computer science)

As a triangle exchange is referred to in programming a method for exchanging the values ​​of two variables. In this case, an auxiliary variable is used to latch the value of the variable, which is first overwritten. A typical application of the triangle exchange is, for example, in some sorting algorithms such as bubble-sort. The general principle is as follows:

If it is linkable binary values ​​with the values ​​of the two variables to be replaced, you can barter through repeated XOR operations ( taking advantage of the law (A xor B) xor B = A) also realize entirely without auxiliary variable:

Two other possibilities for exchanging ordinates without auxiliary variable is by repeated addition and subtraction:

Or:

This only works for integers, otherwise it could lead to extinctions in floating point numbers. Strictly speaking, there is no longer a triangle exchange.

In some languages ​​(including C ) and when the data type supports binary XOR operation, does the statement

In which

Stands.

For numeric values, also works:

Some languages ​​, such as Ruby or Python that support multiple assignments, creating a triangle exchange is unnecessary:

• Programming