According to declarationIs a statement in a program that lists a set of variable names and specifies the type of those variables.
Such as C, C++, Java
Implicitly declaredBinding of a variable name to a type by some default convention
For example, in Fortain, a value that begins with the letters I, J, K, L, M, or N (or its lowercase counterpart) is implicitly declared as Integer. Otherwise, type Real.
// all implicitly declared variables are global by default, whether inside or outside a function
count = 10;
Implicit declaration is a little convenient, but it is considered to be bad for the readability of the program, because it may bring hidden errors and bugs.
Implicit declarations are also available in Perl, but to avoid these problems. It does something
1. The default scalar, beginning with the character $, can store strings and Numbers
2, the default is an array starting with the character @
3. Default is a hash structure starting with the character %.