In C language, l usually represents the long integer data type. Its purpose is to store values ??beyond the range of ordinary integers. Since ordinary integer data types can only store values ??between -2,147,483,648 and 2,147,483,647, and program errors may occur due to values ??that are too large or too small, the long integer data type is essential.

Another way to use l is in numeric literals in the C language. This l represents a long integer, which is usually used to distinguish ordinary integers. For example, when a program needs to store a value that is larger than the storage range of a regular integer data type, we can add l at the end of the number to indicate that it is a long integer.

In addition, in the C language, l can also be used as part of a string literal. It represents the length of the string and is usually used with the strlen() function. Because the string may contain arbitrary characters, and we need to know the length of the string to allocate enough storage space, l is very useful in this case.