“{var1} someString”和“$ var1someString”之间有什么区别？

Question

I can make out the difference between

echo "{$var1}someString" // here the variable is $var1
echo "$var1someString"   // here the variable is $var1someString

The question is why to use {}? It works only with {}. It does not work with (). What is so special about { }?

Answer 1

you expained it yourself. thats simply the syntax php uses for this - nothing more. to quote the documentation:

Complex (curly) syntax
Simply write the expression the same way as it would appear outside the string, and then wrap it in { and }. Since { can not be escaped, this syntax will only be recognised when the $ immediately follows the {. Use {\$ to get a literal {$