如何排序的C函数？ ＆QUOT;函数previous隐式声明在这里和QUOT;错误
问题描述：
我敢肯定，这已被问过，但我找不到任何可以帮助我。
我有在C函数的程序看起来像这样
I'm sure this has been asked before, but I couldn't find anything that would help me. I have a program with functions in C that looks like this
function2(){
function1()
}
function1 (){
function2()
}
main () {
function1()
}
这是比这更复杂，但我使用递归。我不能安排文件中的功能，使各功能只会调用上面本身特定的功能。我不断收到一个错误
It's more complicated than that, but I'm using recursion. And I cannot arrange the function in the file so that every function would only call functions that are specified above itself. I keep getting an error
main.c:193: error: conflicting types for 'function2'
main.c:127: error: previous implicit declaration of 'function2' was here
我如何避免这种情况？感谢您事先的建议和答案。
How do I avoid this? Thanks in advance for suggestions and answers.
答
您使用前需要先声明（没有定义）至少一种功能。
You need to declare (not define) at least one function before using it.
function2(); /* declaration */
function1() { function2(); } /* definition */
function2() { function1(); } /* definition */
int main(void) { function1(); return 0; }