In c language, l can represent many things, depending on the context. The common usage is long, which, like int, is one of the basic data types in C language. Long integers can represent values larger than integers, usually ranging from-2 63 to 2 63-1,which requires more storage space, so it takes up more memory than integers. Long integers play an irreplaceable role in computing scenarios that need to deal with massive data or require high accuracy.

In addition, there is a common usage of l, which means type conversion. Because C language does not support automatic type conversion, we need to manually convert some data types to other data types. In this case, we use the conversion operator to complete the conversion. Adding an "l" before the right parenthesis indicating the data type to be converted means converting the data type to a long integer. Usually we use unsigned int conversion to grow integer; Because when an unsigned integer is converted into an integer, its size and sign will change, thus avoiding the integer overflow problem in C language.

In addition, l has other uses. For example, in character constants, l is used to represent wide characters. Wide characters refer to character variables that occupy more space in storage units and are used to represent special character sets of different languages. In addition, in Windows programming, l is usually used to represent Unicode strings. Unicode is a character set that can be globalized on all computers. It is a scheme to encode all characters into numbers, which can convert all kinds of characters in the world into forms that can be processed by computers. Because Chinese characters are also encoded by Unicode sets, we often use character constants starting with wchar_t and l to represent Chinese characters in Windows environment.