7、ubstring with $replacement${string//substring/replacement}Replace all matchesof $substring with $replacement${string/#substring/replacement}If $substring matches front endof $string,substitute $replacement for $substring${string/%substring/replacemen
8、t}If $substring matches back endof $string,substitute $replacement for $substringexprmatch"$string"'$substring'Lengthofmatching $substring*atbeginningof $stringexpr"$string":'$substring'Lengthofmatching $substring*atbeginningof $stringexprindex"$stri