C中小问题？？？

#include <stdio.h>
#include <stdlib.h>
double calculator(double x,char operate,double y);

int main(void){
double x,y;
char operate;
printf("请您输入要操作的数：");
scanf("%f%c%f",&x,&operate,&y);
calcultor(x,operate,y);
return 0;
}

double calcultor(double x,char operate,double y){
switch(operate){

case '+' :
printf("%f%c%f=%f\n",x,operate,y,x+y);
break;
case '-' :
printf("%f%c%f=%f\n",x,operate,y,x-y);
break;
case '*' :
printf("%f%c%f=%f\n",x,operate,y,x*y);
break;
case '/' :
if(y==0){
printf("除数不能为0！\n");
break;
}
printf("%f%c%f=%f\n",x,operate,y,x/y);
break;
defulat :
printf("您输入的为无效字符，请重新输入!");
break;
}
return 0;
}


pc@pc:$ gcc -o calculator calculator_test.c
calculator_test.c:14: 错误： 与‘calcultor’类型冲突
calculator_test.c:10: 错误： ‘calcultor’的上一个隐式声明在此


求高人解决一下，谢谢

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#include <stdio.h>
#include <stdlib.h>
double calcultor(double x,char operate,double y);
拼写错误
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