Should the declaration prototype of the function be declared before the main function?

In fact, for some functions it is a requirement. In order to properly call a variadic function in C ( printf for example) the function must be declared with a prototype before the point of the call. Otherwise, the behavior is undefined.

Why is it necessary to put prototype of user defined function at the beginning of a program?

The function prototypes are used to tell the compiler about the number of arguments and about the required datatypes of a function parameter, it also tells about the return type of the function. The compiler does not find what is the function and what is its signature. In that case, we need to function prototypes.

Should I put functions before or after main?

For a function defined in the same file where main is defined: If you define it before main , you only have to define it; you don’t have to declare it and separately define it. If you define it after main , you have to put a matching prototype declaration before main .

Which is more effective while calling the functions?

5. Which is more effective while calling the functions? Explanation: In the call by reference, it will just passes the reference of the memory addresses of passed values rather than copying the value to new memories which reduces the overall time and memory use. 6.

Can you declare a function without defining it?

Declaring a value–without defining it–allows you to write code that the compiler can understand without having to put all of the details. This is particularly useful if you are working with multiple source files, and you need to use a function in multiple files.

Can we define function before main function?

Function prototypes are not required in C99. Declaring functions before the point of the call and defining them after the point of the call is a popular approach to structuring the program code. Such functions are declared in header files and defined in implementation files.

Which is more effective while calling the C++ functions *?

5. Which is more effective while calling the functions? Explanation: In the call by reference, it will just passes the reference of the memory addresses of passed values rather than copying the value to new memories which reduces the overall time and memory use.