我有两个我想要循环的数组.我正确地构造它们,然后在进入for循环之前,我确实回应它们以确保数组的一切正常.
但是当我运行脚本时,它输出一个错误:
l<=: syntax error: operand expected (error token is "<="
我咨询了强大的谷歌,我明白它缺少第二个变量,但我之前提到我确实回应了价值观,一切似乎都没问题.这是片段..
#!/bin/bash
k=0
#this loop is just for being sure array is loaded
while [[ $k -le ${#hitEnd[@]} ]]
do
echo "hitEnd is: ${hitEnd[k]} and hitStart is: ${hitStart[k]}"
# here outputs the values correct
k=$((k+1))
done
k=0
for ((l=${hitStart[k]};l<=${hitEnd[k]};l++)) ; do //this is error line..
let array[l]++
k=$((k+1))
done
for循环中的变量被正确回显,但循环不起作用..我在哪里错了?
#
正如gniourf_gniourf回答:
“… At some point, k will reach the value ${#hitEnd[@]}, and this is
exactly when hitEnd[k] is not defined and expands to an empty string!
Bang!”
意思是错误输出不显示在循环的开头,但是当k的值大于数组的索引时,指向该数组不包含的索引…
解决方法:
那是因为在某些时候${hitEnd [k]}扩展为空(未定义).我得到((l< =))相同的错误.您应该将for循环写为:
k=0
for ((l=${hitStart[0]};k<${#hitEnd[@]} && l<=${hitEnd[k]};l++)); do
以便总是有一个索引k对应于数组${hitEnd [@]}中的已定义字段.
而且,而不是
k=$((k+1))
你可以写
((++k))
完成!
使用更好的现代bash练习修改您的脚本:
#!/bin/bash
k=0
#this loop is just for being sure array is loaded
while ((k<=${#hitEnd[@]})); do
echo "hitEnd is: ${hitEnd[k]} and hitStart is: ${hitStart[k]}"
# here outputs the values correct
((++k))
done
k=0
for ((l=hitStart[0];k<${#hitEnd[@]} && l<=hitEnd[k];++l)); do
((++array[l]))
((++k))
done
现在,我不太确定for循环是否完全符合你的要求……难道你的意思不是这样吗?
#!/bin/bash
# define arrays hitStart[@] and hitEnd[@]...
# define array array[@]
#this loop is just for being sure array is loaded
for ((k=0;k<${#hitEnd[@]};++k)); do
echo "hitEnd is: ${hitEnd[k]} and hitStart is: ${hitStart[k]}"
# here outputs the values correct
((++k))
done
for ((k=0;k<${#hitEnd[@]};++k)); do
for ((l=hitStart[k];l<=hitEnd[k];++l)); do
((++array[l]))
done
done