In C language, what happens if a function is called before it is declared?

If we do not use some function prototypes, and the function body is declared in a certain part after the statement that calls the function. In this case, the compiler assumes that the default return type is integer. But if the function returns a value of another type, an error will be returned. This works fine if the return type is also an integer, it may sometimes generate some warnings.

Sample Code

#include<stdio.h>
main() {
   printf("The returned value: %d</p><p>", function);
}
char function() {
   return &#39;T&#39;; //return T as character
}

Output

[Error] conflicting types for 'function'
[Note] previous implicit declaration of 'function' was here

Now if the return type is integer then it will work.

Sample code

#include<stdio.h>
main() {
   printf("The returned value: %d</p><p>", function());
}
int function() {
   return 86; //return an integer value
}

Output

The returned value: 86

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