# 015. `merge(x, y, cond)` topic: {ref}`conditionals` `merge(x, y, cond)` returns `x` if the condition `cond` is true, otherwise `y`. We can get the same result as the previous tip: ```{literalinclude} ../../src/merge.f90 :language: fortran :caption: merge.f90 | |

``` ```{code-block} text :caption: Output[^gfortran-version] -1 negative 0 zero 1 positive ``` [^gfortran-version]: Compiled using `GNU Fortran (Ubuntu 11.3.0-1ubuntu1~22.04) 11.3.0` with no flags Similar to the three-argument usage of [`numpy.where`](https://numpy.org/doc/stable/reference/generated/numpy.where.html). ---

merge(x,y,condition) returns x if condition is true, otherwise y. Same output as previous:

integer :: i
do i=-1,1
print*,i
! "zero" padded to have same length as "negative"
print*,merge("negative",merge("zero ", &
"positive",i==0),i<0)
end do
end
— FortranTip (@fortrantip) December 18, 2021