#include<stdio.h>
int main (void)
{
    int result= abc(6)    ;
    printf("the  number is %d\n",result);
     return 0;
}
void abc (int x)
{
    if (x == 0)
    return 1;
    else
{
    int recurse = abc(x-1);
    int result = n*recurse;   
    return result;
}
}
错在哪呢？

void abc (int x)
改
int abc (int x)

并且把函数写在main的前面

解决！

#include<stdio.h>
int main (void)
{
    int abc (int x);
    int result= abc(6)    ;
    printf("the  number is %d\n",result);
    getchar();
    return 0;
}
int abc (int x)
{
    if (x == 0)
    {
        return 1;
    }
    else
    {
        int recurse = abc(x-1);
        int result = x*recurse;   
        return result;
    }
}

#include<stdio.h>
int main (void)
{
    int abc (int x); //你们都不用声明的吗???
    int result= abc(6);
    printf("the  number is %d\n",result);
    return 0;
}
int abc (int x)
{
    static int result =0;
    if (x == 0)
    return 1;
    else
    result = x*abc(x-1);   
    return result;
   }