Why function declaration is important. Here this program is running without declaration

Question

void main()
{
int a;
a=name();
}
int name()
{
int b=7;
return b;
}

Answer 1

In your code snippets there are two functions and both the functions are declared.
Function declaration means stating the return type along with the function name,parenthesis, and body

please be more specific about your doubt

Answer 2

My question is there is necessary to first declare a function. Because without declaration every program is running