所以我在 linux 终端上写了一个程序，我的程序有两个部分。第一部分是除法，第二部分是计算一些数字的 MOD。退出第一部分的方法是将 999 放入任一输入中进行除法。
我的问题是，即使用户输入 999 作为第一个输入，用户也必须输入第二个数字。我想知道这些是否像在 Windows 中一样，您可以在 Linux 中执行 goto:someOtherLocation。这是代码:
echo "Enter the number to divide (dividend) (enter 999 to quit):"
read numberOne
[IF NUMBERONE = 999, JUMP TO SECONDPART]
echo "Enter the number to divide (divisor) (enter 999 to quit):"
read numberTwo
while [ "$numberOne" -ne '999' ] && [ "$numberTwo" -ne '999' ]
do
while [ "$numberTwo" -eq 0 ]
do
echo "You cannot divide by 0, please enter another number:"
read numberTwo
done
RESULT=$(echo "$numberOne/$numberTwo" | bc -l)
echo $numberOne / $numberTwo = $RESULT
echo $numberOne / $numberTwo = $RESULT >> results.txt
echo "Enter the number to divide (dividend) (enter 999 to quit):"
read numberOne
echo "Enter the number to divide (divisor) (enter 999 to quit):"
read numberTwo
done
SECONDPART
counter=1
totalCount=0
temporal=0
while [ "$counter" -lt '101' ]
do
temporal=$( expr $counter % 5)
echo $counter MOD 5 = $temporal
echo $counter MOD 5 = $temporal >> results.txt
totalCount=$(echo "$totalCount+$temporal" | bc -l)
counter=$(echo "$counter+1" | bc -l)
done
average=$(echo "$totalCount/100" | bc -l)
echo The average of all the MODs is $average >> results.txt
如上所示，如果输入是 999，我想从输入直接跳到第二部分。
像 sh 和 bash 这样的 Bourne shell 没有 GOTO 语句。这是considered harmful .
相反，使用像 if 语句这样的结构化流程控制:
echo "Enter the number to divide (dividend) (enter 999 to quit):"
read numberOne
if [ "$numberOne" -ne 999 ]
then
echo "Enter the number to divide (divisor) (enter 999 to quit):"
read numberTwo
while [ "$numberOne" -ne '999' ] && [ "$numberTwo" -ne '999' ]
do
while [ "$numberTwo" -eq 0 ]
do
echo "You cannot divide by 0, please enter another number:"
read numberTwo
done
RESULT=$(echo "$numberOne/$numberTwo" | bc -l)
echo $numberOne / $numberTwo = $RESULT
echo $numberOne / $numberTwo = $RESULT >> results.txt
echo "Enter the number to divide (dividend) (enter 999 to quit):"
read numberOne
if [ "$numberOne" -ne 999 ]
then
echo "Enter the number to divide (divisor) (enter 999 to quit):"
read numberTwo
fi
done
fi
counter=1
totalCount=0
temporal=0
while [ "$counter" -lt '101' ]
do
temporal=$( expr $counter % 5)
echo $counter MOD 5 = $temporal
echo $counter MOD 5 = $temporal >> results.txt
totalCount=$(echo "$totalCount+$temporal" | bc -l)
counter=$(echo "$counter+1" | bc -l)
done
average=$(echo "$totalCount/100" | bc -l)
echo The average of all the MODs is $average >> results.txt
它可能看起来比一个简单的 goto 更笨拙，但是当您利用更结构化的控制流时，代码会变得更易于阅读和遵循:
readNumber() {
local number
read -p "$1" number
[ "$number" -ne 999 ] && echo "$number"
}
while one=$(readNumber "Enter dividend or 999 to quit: ") && \
two=$(readNumber "Enter divisor or 999 to quit: ")
do
echo "$one / $two = $(echo "$one / $two" | bc -l)" | tee results.txt
done
这会一直要求除数，直到用户为其中任何一个输入 999。