"Variable not found" error issued by the shell

Question

if [ "$1" = "" ]
then
       echo -n "Gib das Startkapital ein: "
       read kapital
else
       kapital  = $1
fi

echo $kapital

When I say kapital = $1 it says that this variable does not exist:

$ sh zins.sh
zins.sh: 16: zins.sh kapital: not found

Answer 1

Unlike free-format languages like C, the shell is white-space sensitive in many places, and one of them is the = in assignments. Use

kapital=$1

and it will work.