你不具备使用”_”，你可以。提案中提供的示例包括信用卡号，电话号码或仅在代码中使用分隔符的数字。
对于“在期望数字串的位置”，它只是在应该以数字开头（或结束）的地方。这里有些例子。
请注意，根据此建议，下划线只能放在数字之间。不能将它们自己放置在通常期望数字串的位置：
int x1 = _52; // This is an identifier, not a numeric literal.
int x2 = 5_2; // OK. (Decimal literal)
int x2 = 52_; // Illegal. (Underscores must always be between digits)
int x3 = 5_2; // OK. (Decimal literal.)
int x4 = 0_x52; // Illegal. Can’t put underscores in the “0x” radix prefix.
int x5 = 0x_52; // Illegal. (Underscores must always be between digits)
int x6 = 0x5_2; // OK. (Hexadecimal literal)
int x6 = 0x52_; // Illegal. (Underscores must always be between digits)
int x6 = 0x_; // Illegal. (Not valid with the underscore removed)
int x7 = 0_52; // OK. (Octal literal)
int x7 = 05_2; // OK. (Octal literal)
int x8 = 052_; // Illegal. (Underscores must always be between digits)
