What is the purpose of the inline keyword in the C language?

The inline keyword in C language is used to instruct the compiler to expand the function in an inline manner. Inline functions are a special type of functions that are expanded directly at each call point, rather than being executed through a function call. Using the inline keyword can improve the efficiency of the code, as it avoids the overhead of function calls.

The purpose of the inline keyword is to instruct the compiler to insert the code of a function directly at the point of the function call. This helps reduce the overhead of function calls and decreases the stack overhead of function calls. The expansion of inline functions is determined by the compiler and is not mandatory; the compiler can choose whether to expand the function inline.

Function declarations using the inline keyword are typically placed in header files to allow them to be used in multiple source files. This allows the compiler to directly insert the function’s code at the calling point during compilation. However, it is important to note that when the function’s code is long or involves complex operations such as loops or recursion, using the inline keyword may lead to code bloat, which can actually decrease efficiency. Therefore, when using the inline keyword, it is essential to weigh the pros and cons and make a decision based on the specific situation.