The C99 predefined identifier __func__ makes a function name available for use within the function. Immediately following the opening brace of each function definition, __func__ is implicitly declared by the compiler. The resulting behavior is as if the following declaration had been made:
static const char __func__[] = "function-name";where function-name is the name of the lexically-enclosing function. The function name is not mangled.
The function name is qualified with the enclosing class name or function name. For example, if foo is a member function of class X, the predefined identifier of foo is X::foo. If foo is defined within the body of main, the predefined identifier of foo is main::X::foo.
The names of template functions or member functions reflect the instantiated type. For example, the predefined identifier for the template function foo instantiated with int, template<classT> void foo() is foo<int>.
For debugging purposes, you can explicitly use the __func__ identifier to return the name of the function in which it appears. For example:
#include <stdio.h>
void myfunc(void) {
printf("%s\n",__func__);
printf("size of __func__ = %d\n", sizeof(__func__));
}
int main() {
myfunc();
} The output of the program is:
myfunc
size of __func__=7 Related information