c++函数调用中参数太多

Question

#include<stdio.h>#include<string.h>int main(){char fun();char a[20],e,b[200];int b;gets(a);scanf("%c",&e);fun(a[20],e);}char fun(char a[20],char b){int i;for(i=0;i<20;i++)if(a[i]==b)a[i]=a[i+1];return a[20];}