函数没定义

Q:

 

#include<stdio.h>
int main()
{
char A,B,C,D,s;
float z;
float x,y;
printf("if you want add input A\nsubtraction input B\nThe multiplication input C\ndivision input D\n");
scanf("%c",&s);
scanf("%f%f",&x,&y);
if (s==A)
{
he(x,y);
}
if (s==B)
{
cha(x,y);
}
if (s==C)
{
ji(x,y);

}
if (s==D)
{
shang(x,y);

}
return(0);

}
void he(float x,float y
{
float z;
    z=x+y;
    printf("liang ge shu de he is %f",z );
}
void cha(float x,float y)
{
float z;
    z=x-y;
    printf("liang ge shu de cha is %f",z );
}
void ji(float x,float y)
{
float z;
    z=x*y;
    printf("liang ge shu de ji is %f",z );
}

void shang(float x,float y)
{
float z;
    z=x/y;
    printf("liang ge shu de shang is %f",z );
}

老师，这个哪里错了？

A:
A,B，。。要写成'A'
main()中你对函数没有声明